Some people like them some don't, so yes, try to hear them before you buy.
I had Def Techs for about 10 years. Liked them alot. (Larger sweet spot mainly.) Read a lot about their anti-thesis (in a way): Vandersteen. Time aligned, phase coherent, direct radiators. Set up a 7.1 system. I did like the Vandersteen more for music (very small sweet spot though), but the sins of the Vandersteen system for HT were, to me, much worse than the sins of the Def Tech system for 2 ch stereo. So I then moved upscale (in a way), and got a system with Mirage speakers.
You might try a search on Definitive Technology, Def Tech, Mirage, etc, because there have been a lot of comments on what people like and don't like with these kinds of speakers.
For kicks, here is a review of a Mirage pair that sort of highlights to me what I like about bipolar/omnipolar speakers:
http://h1.ripway.com/kevin5brown/Mirage-OM-5.pdf
(I got the OM-7's, because I don't believe that subs in L & R speakers is the best way to do things. The best place for sub(s) in a room is most times not the same place you'll place your L & R speakers. When I had Def Tech, I had BP-30s.)
