A lot of good advice here and seems like you already know some of the ins and outs of both bodies. You really can't go wrong with either body regarding image quality so you'll want to consider some other issues. From my experiences with the Rebel bodies, there aren't separate wheels for adjusting aperture and shutter speed. In other words, it'll require going into the menu system in order to change them separately. Maybe it's not a big deal but it could mean the difference in getting the shot and missing it. For ergonomics, I found even the 10/20/30/40D bodies a bit small for my hands. My pinky always ends up under the camera body. This could become more of an issue with the even smaller Rebel bodies. Again, not a big deal but something to consider. Assuming you start going for the bigger glass (i.e. 70-200 f2.8is, 24-70 f2.8is, etc...) the smaller rebel body feels a little out of balance.
Anyway, just some things to consider...