I have used it live for 3 gigs and 20-30 times jamming with friends.
My biggest tip is keep it simple! When you're live everything becomes a bigger deal than you think.
For instance, last time I played here's all I did: I looked at each track in our setlist, which are stored as Ableton live sequenced files. For each track I asked myself, 'what are the 1 or 2 aspects of this track that i could re-create in realtime by playing the mpc pads'. I figured that out, and muted those channels, then rendered the full ableton mix minus those channels.
Then I took all the audio from the missing channels, and pulled them into recycle. (You could also chop on the mpc.) I picked out all the best chops, then used bluebox to make a program for each song.
It worked really well, best gig yet with these guys. I am feeling confident with my pad-hitting skills, so I was mixing a cdj with one hand and bashing on pads a lot with the other. I used the q-link to change pitch and do a few 'fake scratches'. The crowd seemed to take notice and enjoy it.
That was for my hiphop set with mc's, where I play more of a 'dj' role.
I'm working on a techno set for this summer, using a machinedrum, mpc1k and mixer/fx. I will play full sequenced tracks plus live fills from the mpc, using all 6 outs onto separate mixer channels. Then I will fade over to the machinedrum while I load each new track onto the mpc, then mix back to the mpc.
Hope that helps