The issue that you have with your 28 f/2.8 IS is most likely something that can be solved with AFMA because it focuses accurately with LiveView.T3i doesn't have AFMA...though I agree with you, it's something it would solve (and the 7D2 would have AFMA)
That said, if you've already got the 24-105, I don't see the point of having the 28mm. That extra stop won't make as big a difference as having something like a 35mm f/2 or 30mm f/1.4 would.
How about a 7D2, the 10-22, and a Sigma 18-35?Sigma 18-35 would also be a nice option. You could turn the 10-22 and 28mm into a 10-18 and 18-35 and come reasonable close to break even.
Part of it depends on what you shoot. Unless you are doing night photography or some action work in mixed light, I don't find the wide, fast lenses that great on crop cameras.