Haha the size of the room and number of speakers has generated almost as much interest as the SS8s themselves! Thanks for the comments, everyone. I agree with you all that the room is too small for what I'm trying to do with it

. When I first moved in I considered using other rooms but this current one won out for a number of different factors, and in the years since has proven to be an excellent choice. Perhaps one day I will move to a house and have a bigger room to play with (and not have to worry about the neighbors so much), but that's hard to justify when I already have more space than I really need as a single guy. So, for the moment, the room itself is non-negotiable.
With that being said there are three different things that I use the speakers for:
Even though, like many others, the time I spend listening to music has increased since I got Salk speakers, all three of those are important to me, and that might help to explain how I got to where I am now.
Music: In answer to your question, dB Cooper, if all I listened to were 2-channel music then I definitely wouldn't need a sub. I actually
did use it when I had SongTowers as mains, but that was primarily because it was already there and I thought it sounded a bit better; I would have been fine without it, though. With the SS8s I no longer use a sub when listening to music.
Movies: For movies, on the other hand, I think a sub definitely makes a difference. I don't think it's necessary, by any means, but it is often used in modern movies in scenes that wouldn't sound the same without one, in my opinion. I also very much enjoy surround sound in movies, despite it being underutilized. 7.1 is overkill, but I think having some surround/rear speakers noticeably enhances the experience, however subtle it may be.
Games: In games, on the other hand, 3D positional audio makes a
world of difference to me. I have realized that I am in a fairly significant minority when it comes to caring about audio in games, and so this is probably a bit hard to identify with, but I think it really improves how immersive a game is, even more than graphics do (and this is coming from someone who programs graphics for games for a living). I wouldn't really ever consider not having good quality surround sound in my entertainment system, and the closer the sounds in back of me match the sounds in front of me the better.
Finally, there's the attachment to speakers that were created specifically for me. When upgrading to the SS8s it probably would have made more practical sense to sell the SongBirds, but I found myself reluctant to do so since they were custom Salk made and matched the others. On the other hand, I thought it would be interesting to see what 7.1 was actually like, and being single seemed like an ideal time of life to go a bit overboard on something like this, so that's how it all came about.
Interestingly enough, when it comes to the actual sound quality I have noticed that the size of the room seems to be much more of an issue when it comes to 2-channel music, rather than having so many other crowded speakers in there. Besides the issues of physical space I actually really enjoy having the surrounds and rears, even though they're so close to my listening position. I often think, on the other hand, that having just a bit more space (especially to the left and right) would probably help the soundstage when it comes to music. I've done my best with acoustic treatments to try and make up for this, though, and I'm actually pretty happy with my little setup and how it sounds.
Oh, and:
Can you give us an idea of your room dimensions?
Very approximately 10' x 14'.
Thanks again everyone for your interest,
John-Paul