I recently went through the same type of search. I had a XTi, upgraded to better glass (24-70L 2.8) and started searching for a new body. For me it came down to the 7D or the 5DII. What concerned me is, knowing that the lens makes the most difference the image quality, would there be a big change just from the body upgrade? Would the the expenditure show in the quality of the images. In short — absolutely. I got the 5DII several months ago and have been blown away by the image quality (with the same lens). Versus the Xti, the 5Dii has sort of an ethereal "3D" quality to it. I've even had people notice the change, asking what I had done differently. If you end up getting the 5DII to use with the L series lens, don't worry about making a smart choice — it truly is an incredible and noticeable upgrade.