I agree the SP-808 is awesome. You can do so much with the samples. Putting them on the song map to make customized phrases, and putting them back on the sample pads is a big plus. Resampling internally at will is also a very nice commodity to have.
My only gripe about the 808 is that it is completely useless without a disk in the drive. For instance, I was playing a party and my mixer fried out before I started playing, so I ran my MC-303 through my SP-808, and it sounded fine, but whenever I switched songs on the 808, the sound of the 303 would cut out for a couple seconds. THat's more then enough for the crowd to get pissed, but when I switched disks, the sound cut for almost half a minute. Other then that, and of course the polyphony issue, the 808 is the bomb!