Thanks for asking this question here. I've reviewed discussions of so-called "flow neck" putter designs on a number of forums:
and am frankly a bit disappointed in the low-level of knowledge people display when expounding their very "authoritative" views on the subject of putters.
Basically, the design of the putter usually hurts and almost never helps, and all the claims that this or that feature benefits golfers in general or this particular golfer specifically is utter nonsense logically and scientifically. It's just salesmanship crap, from uneducated people who manufacture whatever seems to sell.
For example, so--called "toe flow" is nonsense junk from Scotty Cameron. Yes, different designs of putters will "close" more thru impact than others. So what? Is that desirable? On what planet would a golfer think that the degree the putter face changes orientation thru impact is a good thing and then entrust that degree of closing to some designer wearing seafoam green cashmere sweaters in his Malibu bungalo?
For goodness sakes, people, now hear the news:
Science absolutely proves that putter design features don't matter, because any help they might offer is too miniscule compared to the normal variability in human performance. What hurts a putter is goofy designer claims and features that detract from plain-jane use of the tool to perform its appointed task: rolling the ball nicely where aimed (or at least where intended) consistently and accurately with the appropriate touch. Aside from that, design features DON'T HELP enough to notice.
With respect to the hoseling, this is just stupid stuff. The offset hosel arose rom trial-and-error by people hunting in the dark for something that worked better given their personal incompetencies stroking balls on a line. For heaven's sake! Who ever invested these design features with infallibility as if they were designed by God himself? Uh, you did.
So-called "flow neck" putter designs don't make the ball roll off the face in an undesirable line -- the golfer swinging it does.
Is it not a sad commentary on golf culture and golfers generally that they persist remarkably in the face of common sense in the belief that the putter design CAUSES results when the golfer swings it? No putter CAUSES bad strokes; golfers ALONE cause bad strokes, no matter what the characteristics of any tool that is at least in the ballpark of tools referred to as "putters".
Any golfer who causes a bad stroke with any reasonable putter design is the CAUSE of the bad stroke.
So why do golfers always lust ignorantly after the supposedly superior design in a putter? To be charitable about it, perhaps the golfers think the putter design will save them from themselves because they are either not competent in making serviceable strokes with any putter or they are inattentive to performance or they are wetting their pants in a flood of overwhelming anxiety and fear when they play this game.
That's about as charitable a view as one can reasonably muster when observing this lust for putter designs, giving credence to claims of marketers at Titleist and similar shops.
News flash: Scotty Cameron does NOT believe in his design features and says candidly when asked that his design features don't make any difference -- he admits he is selling only eye candy. He has said this publicly a number of times. The problem is that he doesn't say it to golfers when he markets his putters to them.
What real difference does the hosel pattern make?
1. An offset putter hosel like the plumber's neck or the flow neck is not ordained by God and did not arise in the evolution of putters in the same way the chimp learned to walk upright and later learned to speak Russian and conquer other tribes with Modern Marvels of Warfare like the Abrams M-! Tank or the Patriot Missle defense system. It's just some goof's trial and error and it worked for him, but who cares?
2. An offset hosel "influences" the physics of what the putter face "might" do thru impact, but what actually happens depends on what the golfer does, mostly with his grip pressure in the manner of torquing the handle into the human body that swings the putter. There are plently of such "influences" but they all just constitute the tool the golfer is using, and the golfer needs to learn HOW to use whatever tool he is wielding. The crazy idea that a little curvature in the hammer changes what has to happen at impact seems to be one that golfers en masse salute like good corporals in the Kaiser's trenches.
3. Visually, offset hosels are just dumb, because they complicate the brain's sense of what is being swung by the human body -- the end of the stick at the point where the hosel changes direction off the shaft, or the sweetspot of the putter head? Golfers who swing one time the hosel and another time the sweetspot cannot then blame the design when some strokes pop out to the right. If you swing an offset putter by swinging the end of the shaft, when the sweetspot is further along towards the toe, the ball is likely to get sent off line to the outside. Don't blame the design physics, because the physics is utterly known and predictable and reliable. But the golfer not knowing that the offset design resulted in his lack of competence in swinging the putter in a way that CAUSED the ball to go off to the outside is really one of those situations when the mature response ought to be either "I should have known about how to use this goofy putter so I swung the sweetspot of the putter head thru the ball and didn't get messed up by this design", or "thanks a lot, boys at the putter manufacturing company, for your "cutesy" effort to be helpful -- all you did was mess up my game."
Putter design features that depart from a reasonably plain and straight forward slab at the end of a straight stick are NOT helping: they are on balance almost always hurtful to the golfer simply using the toll for its ordained purpose -- rolling the ball where intended (if not more efficaciously, wherever aimed). The manufacturer's claims that the features are helping aiming, stroking, hand position thru impact, solid contact, maintaining line integrity during off-center impacts, true-roll forward spin off the face, etc. etc. etc. ad nauseum are all worthless "puuffing".
Any reasonable putter design can and should beat out the performance of a tricked up putter. A goofy big-head design (very popular since about 2005) undercut the aiming and swinging of the putter due to the goofy visual processing the brain has to perform not to get surprised by something in the quirky complexity of the head shape and appearance. That's Brain Science 101 if any one cares to check it. Similarly, science proves that a putter with a feature that allows a BAD golfer to slightly improve the competence of his handling of the tool can and often does outweigh a supposedly superior feature, as the same golfer will do worse with this supposedly better design. Want details? Read Werner and Grieg, How Golf Clubs Really Work and How to Optimize Their Designs.
To answer your question, the putter design does not much at all influence whether it is "better" for a straight-back, straight-thru stroke or an inside arcing-inside arcing stroke. What influences that is the use of a minimum grip pressure that cancels out and overrides the undesirable physics influences tending to swing the putter face open in the backstroke, which influences are present in BOTH toe-hanging and center-shafted face-balanced putters. Heel-shafted putters are infected by this influence marginally more than face-balanced putters, but even face-balanced putters will open in the backstroke unless the golfer has the skill to grip it with more than the often recommended "girly grip" that features "sensitivity in the fingers" a la Utley and Stockton. This poor, ill-advised counsel will sink your skill with the putter or at least drop-kick your butt into the world where you NEED help from a seafoam-besweatered designer to get your strokes back to their manly ordinariliness. What a stupid place for a mature golfer to find himself.
To answer the question a bit more directly, no, no one makes a "flow neck" design that attaches to the center of the face and results in a face-balanced "flow neck" putter. It would be possible, but visually disturbing, as then the hosel would get in the way of the putter face sweetspot and the back of the ball. Some folks make an offset hosel that enters the center of the putter head from the rear, and these designs were considered by scientists testing putters in the 1960s as the best designs they had tested (Cochran and Stobbs, Search for the Perfect Swing, 1968, on "Backassward" putters). That speaks volumes about the stupidity of marketing claims about plumber's neck and flow neck designs being generally better than other designs. They aren't; they are a bandaid design for people that don't have anything to do with a competent and skillful use of the tool.
It's a stick -- swing it so the ball rolls where it's supposed to go.
Sorry if I get a bit "testy" but hardly any one in golf culture does much more than repeat what they heard someone else say. It's a veritable blizzard of oftentimes smugly presented nonsense that makes a perfect "whiteout" for the progress of golf.
Putting Coach and Theorist