When considering the enclosure- virtually a requirement for coolant, which is itself a requirement for production work- I can "a'la carte" an $8,700 440. A similar setup for the 770 is closer to $14,000, plus the additional shipping cost of the larger, bulkier machine. (Another $500-$700.)
Rounding off a bit, I can have an enclosed, ready-to-go 400 on the floor for $10K, or an enclosed, ready-to-go 770 for $15K. That extra five grand is not a trivial amount of money for me.
Plus there's still the nontrivial size aspect. You might not understand that when I say I have "no room" in my shop, I mean there is zero room.
I'm currently working on a dust enclosure for my Shapeoko router, and I have no idea where I'm going to put that when it's done. It spent last winter on sawhorses in front of the machine room's main door, because I had no other place to put it. The new big Exacto mill, at the moment, can't be fully used because at certain places, the table runs into the Logan lathe on one side, or the wall on the other side.
All that considered- and the fact that I'm still a green enough newbie I don't need to be diving into tool changers and 4th axes yet- I believe that, for the time being, I would be better served by the 440.