Is your experience with the pi at 700MHz or at the higher (now supported) speeds? Since the higher speeds also increase the memory speed, you actually tend to get more performance than the clock increase alone would suggest.
Also, did your tests use the hardware accelerated video?
It will also be interesting to see what difference the added memory of the new version will make. Since most xbmc distros allocate 128M for video, this takes the memory available for the rest of the system from 128M to 384M.
It's nice to see what economies of scale can do for the costs of components :-)