Nick-
First of all, you might want to consider QS4s with your size room and then investing that savings into a second pair or a pair of direct-radiatings for the rear.
I have not personally heard true 6.1 or 7.1 yet, but I am fully confident that it will be better. Think about the difference you heard between Pro Logic and 5.1. The distinct sound isolation was amazing. Now, take that same concept and think about doubling the possible distinct channels for movies to utilize. There's no way that can't sound better when they really start utilizing it. Movies with that "drive-by/fly-by" sound in the rear will probably have a smoother transition in the rear between L & R speakers. Plus, just think about how good SACD & DVDA will sound when they start recording in 7.1. Man.....I'm drueling over here.
I am in the process of finishing my basement, so I can empathize with your decision process. I went ahead and wired out for 7.1, but don't yet have the rear surrounds or a receiver that can do 6.1 or 7.1. However, I am quite sure that will change. There's no way I'm going to be able to sit and look at those wires and not want to know what it sounds like.
Good Luck
