Well, as if anyone else cares, I'm LOVING my DJM 500, no matter how dated it may be these days. The sound isn't as good as my DXM06, and it may not have the kills, but I've gotten used to it and I'm loving it. My only major quibble is the effects in it. There's no beat-synching button for them so they wind up sounding out of whack. I've decided to not really use the mixer's effects but just use the built-in effects on my cdjs.
Another question is the bpm counter on the mixer seems to always be one bpm off of what the cdjs say. Like usually I'll play a track at 130 bpm and the mixer says it's at 129 bpm, both on real and average settings. I've resorted to just trusting the cdjs and their readings of the bpms since they always match, and I'm guessing have newer bpm technology than the DJM 500.