Hi SBA
Thanks for your kind words.
In short I absolutely love my canoe, and wouldn't trade her for another canoe. To answer your questions,
The 15" ultra lite Prospector I have handles better fully loaded, and with a paddle partner then when I solo, and empty. The one disadvantage to a 48lb canoe is that even with a little wind, she likes to sail. When I was loaded with two adults in her, she was more responsive, easier to keep on course, and kept the momentum of travel better. When I was loaded with my kids, and even loaded and solo, this decreased a little, but I still found her an easy paddle. When she's empty and I'm alone I paddle from the mid section, and find that she is very responsive, but I need to work a bit harder at keeping a steady course. I've been in many different canoes over the years though, and have found that this is common with most canoes when they are empty and soloed in.
In terms of kneeling, I must admit that I always kneel, as I find it physically more comfortable then sitting. Kneeling no doubt offers more stability to the rider and probably adds to my favoring this technique. I have been also working on my "omering" (mid section paddling while leaning the canoe sideways) and find that this has added to my ability to control the boat in heavier winds. Omering felt really weird at first, but has become my preferred soloing technique in winds.
As for gear, a few weeks ago I had my 2 boys in it, and a FULL load of gear. The boat in my mind is at its best then, and suspect that you will find the same true with the 16.6". To test it out try paddling with a few full water jugs in the front (or a mid size rock for that matter) and see how yours handles. One thing is for sure, the Langford Prospector design accommodates a large volume of gear and pack dimensions. Even with two adult packs, two folding chairs, food sack, bundle of wood (it was during the park opener in April that I brought wood as I was unsure of the availability of dry wood in the recently thawed park), 3-six packs, and day pack, along with two fully grown men, the boat could have easily handled an additional barrel.
Is your Prospector an ultra light? Does it have a gel coat exterior finish? An internal finish? All of these things add weight, and stability. Mine has an external gel coat finish (as I wasn't crazy for the "see through" yellow that the non coated ultra lites came in), and really wanted a red canoe, but does not have the inner finish (its a greyish colour). When I tested out various different material options for the Prospector I did notice slightly more stability in the inner coated models, but felt that the added weight of the finish was too much for the little increase in stability, especially since I am usually with gear or company when in my boat.
Hope this helps!
If you have any other questions please ask. Do keep an eye on your seats though, as my rear one snapped and I discovered that it had been stapled together rather then woven. I'm having this repaired this week, but was surprised then TT almost cut his hand on a loose staple. I've been assured this was an over site by Langford, but I would check yours just the same.
So where are you traveling to in two weeks? I'm hoping to be back in the park then as well, and if you wanted to test mine out, I'll let you paddle mine if you let me paddle yours

Jeff P
http://algonquincanoeing.blogspot.com/