I would be interested in seeing an actual study on belt vs. no belt. Everything I read seems like a lot of educated guessing and speculation.
I'd also be curious to take a group of "belts make you weaker" types, give them belts, and take the belts away a group of people who regularly train with belts. (And let's give them a week or so to get used to the switch.) Which will be greater, the increase in the first group's 1RMs or the decrease in the second's? Not exactly scientific, but might be interesting.
Anyway isn't the best of both worlds is to only use the belt for the last one or two warmups and your work sets, and never use the belt for deload/light/recovery days? Your warmup and recovery weights should be increasing as your work weights increase, so your "super raw" unbelted squat will increase, as well.
Trust me, those kind of studies are really not that useful and could not be run long enough to be worthwhile. A week won't do much to get ''used to'' a new technique.
You want the best study out there? Train a full cycle (3-6 months) with a belt on most of the time. Train another full cycle without one. Compare. Mix and match. Do it again with your modifications. The only good study is the one you try for yourself. See TKJTG, he seems to train easily without a belt while Charly for example uses one. Personally, I can't replicate what TKJTG does without a belt. More power to him.
The last part sounds right to me. I usually belt up when reaching around 225-245 lbs because for me, it's around that time that I feel that I need the belt to keep warming up properly. Don't belt up 100% of your lifts but it is an interesting tool when going heavy.
Just my 2 cents.