I dont have and have never used an MPC... but I know that the 2xl has a graphic edit function (like sound editors on computers), which can be helpful in clipping samples to perfection.
Many say the 3 has a much better sound.. others say that theres no difference... that you get out what you put in.
in my opinion the 3000 has a fatter sound while the 2000xl is more accurate and precise. basically comes down to personal preference and how much you want to spend on mpc. hope that helps