I think you're looking at this from the wrong angle Marco, just because at the moment there isn't more discussion about theatre systems 5.1, 7.1 etc is more to do with the fact that there isn't any place to do it, look at it this way, before Sony invented the walkman people didn't see the need to be able to listen to music wherever they were, however nowadays most people have some sort of portable device.
I think a new section would be much the same and would ecourage more people to join and participate, for me a place to talk about getting the best out of my system would be great, as well as help and advice on improvements and upgrades specific to 5.1 or greater.
All i can say is give it a go, you can always bin it if it doesn't catch on, the die hard AOS members will still post regardless, but it may encourage more people to join and perhaps get people who seldom post, to be more involved.