Necro,
I will try to keep this short.....and sweet, like the music.
HT and Multi-channel are actually two separate things but they are played on one system. At least in theory, I know that is kind of contradiction but it is what it is.
HT is mixed to present the film experience with dialog and most of the sound from the action coming from the front and center speakers. Getting all the speakers to match has some benefit in HT but in general the side and rear speakers are used for ambience and sometimes gimicky sound, but certainly not the main presentation of sound. That is not to say that it doesn't matter what you use for the side and rears, just that the source material for the most part doesn't require the same level of sound reproduction from the side and rears. Confused yet.
In my HT I have all Stylos for Front, side, rear, Stage for center and two subs for the heavy lifting, oh yeah and butt kickers attached to the furniture which may cause the chair you are sitting in to lift off the ground once in a while.
Anyway, don't want to get in to a big Miltichanneled music discussion because that has been done before but......once you have a HT setup, you may want to try listening to some really well mastered multi-channel music with a 5.1 quality source. Like a McCormack, Simaudio, Lexicon, Universal Disc Player.
Now when you get in to really well mastered 5.1 surround sound music by the likes of Steve Wilson of Porcupine Tree, and several others that he has done. Then you get to the point where the music demands on the rears is at least equal to the demands placed on the fronts and center. When you get to this level of Multichannel music, it becomes akin to an in and out of body experience.
It is not for everyone......truth be told it is probably too much for some, but I like to experience music not just listen to it. With really great speakers matched at all 6 positions in a 5.1 system and of course playing multi-channel music that is mastered and mixed to be experienced in discrete 5.1 it is truly a different experience than just listening to two channel.
Not that two channel is less, or worse, multi-channel is just different and I personally enjoy it more than two channel, YMMV.
CLXs and Multi-channel always remind me of the warning label on Cialis and Viagra.
Not the part about......."If you experience an erection for more than 4 hours, see a physcian" Although that is true too, but rather the part about ringing in the ears and dizziness, the only way to stop it is to turn your system off, hey it's right on the label, honest.