I go either way... I've been getting into two channel since I repaired the IMF's, but I still prefer the Wall of KEF's filling in (6.0 System).
Now sometimes I listen in
"Enhanced Stereo" which in NAD speak, just means all of the surround/main speakers are fed the same stereo signal (front and rear go mono). I've found that early Stereo Recordings (Jazz and stuff) doesn't seem to have enough information for the surround processing to pull anything to the sides or back. So it sounds more natural in "Enhanced Mode"
Now for newer recordings, generally I prefer
"PLII Music Mode". It just seems more like I'm sitting in front of the stage rather than in amongst the band.
The trick is Surround needs to have all the speakers voiced the same and especially for music. At AXPONA there were 2 demos with surround music and it was unbelievable. It was like you were sitting in the middle of the band.
Before you dismiss, listen to a well setup system.
Now I think Botrytis is all over it... you need to have your system very carefully matched and Audyssy is a must! I think the quality of your AVR is also something to think about. I'm running an NAD T775HD and it does an excellent job of managing the Surround Modes (much better than the Marantz SR6006 I had before). That's not a trivial element of the overall system!
It took me a lot of trial an error to get where I am today, but trust me, once you get something like this pulled together (especially with the caliber of the KEF's and IMF's) you won't have a negative opinion of surround sound ever again!
I love having the option of either 2.0 or 5.1. My main stereo rig is way better for music. Part of that is because my 2.0 gear is just so much better, higher quality, than my 5.1. And part of that is because my music was produced for straight-up stereo. But for movies and sports, I love how 5.1 immerses me in the action.
Moral of the story: 2.0 and 5.1 are different beasts, so you can't expect your surround to behave like stereo, and vice versa. Let each be its own. Or not. Do whatever sounds best to you...
...and if you work at it, your 5.1/7.1 system is your 2 channel system and you have that option right in the same room! I can listen to 2 channel on my IMF's, or on my R107's by shutting down the center and rear and going stereo. There is no reason to have a
"dedicated 2 channel system", unless you want the variety of different gear or the ambience of a different room!
My 2 bits...