I am using the same stands for my surrounds with a couple of old phone books to raise them up a bit.
In addition to a lot of different music, I watched The Matrix Friday night and AC/DC Live At Donnington last night. Surround stuff is great. I wasn't sure if the 10s and the center would be big enough to keep up with an 80 Hz crossover but they are more than fine. I played the AC/DC concert kind of loud. If my speakers needed any breaking in, I'm sure they got it.
I'm also amazed at how good the 20s are for two channel, with and without a sub. There's an interesting track, Yulunga by Dead Can Dance. It has some weird chanting vocals that morphing into a sort of middle eastern thing and a bunch of interesting percussion. About 2 minutes in there is a maraca that is panned hard left. It sounds like it is coming from way outside the left speaker. Fun stuff when I'm in audiophile mode.
Jim