i came from a 500d.
autofocus generally isn't much different from a 500d in terms of speed. in terms of accuracy, i would say that the 5d2 is better, and with the outer points, as long as you lock them into something which has good contrast, they are very accurate, however, the further away the thing you're trying to focus on the less accurate/more easily confused they become.
if you want, i can post some crops of something which have been focused with the outer points.
i actually use all the points on my camera as circumstances dictate. the centre point is the best one to use in difficult conditions but all do a good enough job.
i've never felt that the autofocus on my 5d2 was a step back from the 500d. a little bit of a step forward in servo mode where the extra assist points to seem to do a better job of keeping up with something moving.
i take lots of photographs of little children running around and my 5d2 keeps up just fine.
the af on the 5d2 certainly isn't as bad some would have you believe. it can be very accurate indeed, even at f1.4.