Just a few words here in favour of the 7D....
The 7D has 19 AF points and thery're all cross (+) type so all equally reliable. Additionally the centre AF point uses + and x when used with lenses of f 2.8 or larger.
When using all AF points with earlier Canon bodies, you've always had to obtain focus lock initially on moving subjects with the centre AF point only.Thereafter it will pass AF lock to any of the other AF points as the subject moves within the the pattern of AF points.
With the 7D, you can obtain that AF lock initially with ANY of the 19 AF points, and once focus lock is obtained it still passes AF to the other AF points, which is a big improvement with difficult moving subjects.
Add to that the fact that you can vary the number and pattern of active AF points and it's a pretty impressive AF system IMHO.