Had a few moments Saturday night to experiment with the crs I'm using as a center channel for my 2.3 tls'. Everything sounded fine but I was just curious. With just 2 channel they sure as hell didn't need any help with vocals or anything else that would have used the center channel so I did a very easy a b test using the speaker set up on my receiver. In surround mode with both dts 5.1 and dd 5.1 the soundstage sounded better just using the 2.3s' w/o a center channel speaker. There is no doubt in my mind that it was the tweeters. When I switched back and forth several times you could here the distinct difference in tone and smoothness without any gaps due to no center channel.
You have to wonder if when using any high end floorstanding speakers is a center channel really necessary. I can understand the use in a satellite system but it looks like a waste of money otherwise.
If anyone else has done some experiments with there set up please chime in.