7.1 vs 5.1

I went from a 5.1 to a 8.1 system with 3 subs. It was a Theta/Vandersteen setup. All the speakers were carefully set up and positioned. It was really a waste of money. Added nothing to the original 5.1 setup. Maybe my room was just to small (30x22) for it to matter.
The front 3 speakers is really where all the important stuff happens in a movie, the sides and rears are just ambiant sounds so, going from rears to rears, sides, rear center turned out to be pretty meaningless.
I could see the point if you have a very large room and are seating a lot of people but, otherwise, their is no gain.

Ive used 7.1 and 5.1 both.

What do i currently run?

5.1

;)

7.1 really is not that big of an improvement if you can even really call it an improvement.

if you DO use 7.1, make sure the speakers are really BEHIND you. If yer back is close to a wall then it is just too Gimmiky sounding.

sounds like you have a good room for 7.1... but i doubt it would make much difference.

If you wanna try it out, i would suggest 6.1 first. If it dont float yer boat, then you only bought 1 speaker

I've only had 5.1, though my intention is to do 7.1 if/when the room gets redone. However, my real answer to your question, for what it's worth, is I think it depends on how you derive the 7.1. Since it's not encoded discreetly, 7.1 has to be derived, and something like the Lexicon L7 decoding is supposed to be superb. My guess is that, like many good things in audio, you'll only notice a significant improvement if you set things up real well. I don't know what that is, not having done it myself (yet), but if you read Lexicon's setup description, assessed whether you could do it "right" in your room, and then did so if you decided you could, my guess would be that you'd have a real step up in performance.