I think the 500 has a great sound. Some people say it's different than the other MPCs, but my samples always sound like the vinyl I put into it, I mean no change to my ears before and after I sample a record.
Bedouin, I watched your youtube movie (10min live on mpc500) and have to say the first 3 minutes bored me with you putting your samples right but man ones that beat drops with female voices over them wow real nice