Been at work (in Tokyo right now). A few questions were directed at me, so I'll start with the most recent.
I use ail-flap mixing when I need to maneuver. So I have it in Cruise Mode and Speed Mode (mostly for dodging mid-airs in the zoom). I don't use it in steady thermal circles (Thermal mode). I also want of turned off when I lower landing flaps (causes too much adverse yawing with flaps down).
Tuans definitions for Thermal Mode and Float mode are correct, but the camber settings may not be. I use 1.5-2mm for Float and 3.5-4mm for Thermal. In both cases you're trying to stay at min sink AOA (max CL), but in thermalling, you have the load factor (G loading) to deal with. Normally, you would be at a little higher airspeed to keep the same AOA (G's have the same effect as adding ballast). However, I think the tendency is to fly a bit too slow while tugging on the stick. In that case, a little more camber might help. Also, for tight thermals, you'll be pulling and reducing the airspeed to tighten the turn radius without using excessive bank. If you're gonna slide a bit off the L/D curve to the left, you'll need a bit more camber to stay at min drag.
So, buy this reasoning, straight and level Float would need less camber. You just have to do a lot of early morning glide tests and see what the best camber setting is. It could be a clean and in-section, or more camber. For the Aspire and 4M, I've been pretty happy at 2mm. Overdoing a good thing can be bad, so I don't think throwing in a whole lot of camber without testing is a great idea. Besides, the 4M wing already has plenty of camber built in.
Tuan likes to do testing, so if he comes up with some test data that says 4mm works better for Float, then I'd use it. I've just been to lazy to try beyond 2mm. Although dead air is one of my favorite conditions, I seldom get a chance to practice in those conditions. Perhaps I should experiment, but it's easier to steal Tuan's data. Thanks Tuan