The thing with the MPC is, you need to assign the drums which you are triggering from the MPC on a seperate midichannel. My best guess is that an X8 can pull that off, but I haven't worked with one.
Even the most basic workstations usually have 2 split voices and a "drumchannel". So just look which midichannel the drums are, and which the "normal" synth is, and assign your MPC to that drumchannel. If you're planning on using the sounds on your MPC, just see how to connect the internal midiclocks and keep everything else seperated. So, it keeps it all in sync.
And as for sounds... I reckon that any "real" synth sounds better than a software. But is a matter of taste, though.
However, do ask... why are you using an MPC and an X8? Like I said before, I don't own an X8 (or an MPC for that matter) but by the looks of it, the X8 has a sampling/sequencing part. You could use that instead of the MPC either way I guess.