JB, for a somewhat different view on the surround sound question, note the new review of M60s, etc. in Questions. If you're considering only 5 channel DVD-As or SACDs in which performers are discretely placed in the surround channels, then direct radiating speakers all-around are best. However, for example, I listen to classical only, and the surround channels are nearly always used for ambience alone, rather than placing instruments from the orchestra around you(raising the question as to whether they show significant advantage over a stereo CD using DPLII or Logic 7 for ambience extraction). In these types of recordings the more diffuse pattern of a di-polar or bi-polar surround has an advantage and the bi-polar in particular can also do a reasonably good job with discrete material. Also note that unless the identical speakers have fully-adequate bass, the problems of bass management to subwoofers which complicate DVD-A and SACD play at this time would arise.
