I will be purchasing one of these soon but i dont know which one. I wanna make hip hop beats. I know each of these keyboards have different models, some with more keys than others, is there a significant difference in these models?? Also, ive seen people use MPC's with these keyboards, what do they use it for?? They also use turntables to sample records onto the mpc, but isnt there already a sampler on the actual keyboard? Let me know if u can. thanks.