A lotta people here swear by external keyboard synths, myself included (Kawai K5000S). I mean, the MPC-1000 polyphony is limited, no need to use it up on pads and other stuff that keyboards can do well.
I recommend a keyboard synth when people ask, I just say 1) Hook up the keyboard to MPC In and Out 2) set Local Off on the keyboard 3) Set "Soft Thru = As Track" on the MPC 4) Select the PGM and/or MIDI destination on the MPC Main page, on the selected Track. Then the keyboard can control whatever you want, even MPC samples, and recording the MIDI is as simple as.