on the real.. a good workstation with a mpc you can do anything..
if you don't have the money for both.. get a powerful workstation like the Motif or the triton...
when you get more money add on something new.. like a mo phatt or a proteus..
i use a roland xv-3080 (sound canvas) and an ensoniq asr-x pro (drum machine/sampler). works great for me and the rolands expandability of sounds is very good.
i've never used on myself, but i've seen many hip-hop and r&b cats use the akai MPC effectively.