I currently have the following 3 speakers set up....Infinity Beta 50's as my left/right speakers and the Beta C360 as my center channel.

My question is: Would it be alright to use an additional 2 Beta C360's as surrounds?? I can get them for about the same price as the other Beta speakers I would consider using as surrounds (ES250). The reason I'd consider the C360 is that it's a really great sounding speaker and it projects a very wide sound image...plus it's slightly more efficient and has a greater frequency range.

what do you think? has anyone ever used a center channel as a surround speaker??

When possible, I try to use the same speaker for all 5, although most would say that's only necessary for the front 3. Since most centers are monopole, I guess the question is whether you want to use a dipole or bipole for the surrounds. I think that THX recommends one of the latter. Since many surrounds speakers have a simple switch to change from dipole to bipole, I don't think you have to commit to 1 or the other. I imagine that the diffuse sound of bipole/dipole might be bad for certain types/shapes/sizes of rooms. Purely as a matter of preference, so far I've liked monopole (for more pinpoint sound), although I'm using a Mirage omnipolar at the moment.