I've played on the MPC,and I've owned a Linn 9000. (My car got stolen with the Linn in the trunk.)
The good thingsabout these beasts -as with most every Roger Linn design- is the workflow and thought behind 'em. Plus, they swing like a drummer. No kidding, other stuff does not come close. Hihat is a single pad with an open/close slider on the 9000 (just like a drummer plays it).
If it was me, I'd take the MPC. They both swing nicely, but you can sample into the MPC (without swapping ROMs). The Linn has built-in sounds, though, with separate outputs and hardware mix controls. Guess it's about what you want. Don't get either if you're expecting a "new school" idiot-friendly interface. Get an MPC2000 or later if you want that.
"Your reality, sir, is lies and balderdash and I'm delighted to say that I have no grasp of it whatsoever." -Baron Munchausen