I have the Ren, after being offered an opportunity to pick one up on a wholesale deal thru a friend. To be honest, i never really have used the MPC in the past (2000, 3000, etc) so I dont have much to compare it to (I always used an ASR10 as my outboard, last time I used an MPC was the 60 lol)
So far I have been using it mostly as a plugin in PT. i do wish that - to Thes' point - it just mapped straight out in the DAW but I can get all my tracks bussed to separate tracks one by one, and I feel like there might actually be a way to bus them internally on MPC (the plugin, that is) but I honestly haven't spent a lot of time playing with it. I wish it could work as a standalone, when you hear something and have an idea to bang out, firing up the computer and so on can be a boner killer. But that said it is pretty easy to get going.
Some of the software capabilities are cool. The hardware is great. I dunno, I think if you are looking at something like Maschine, or you are already working in Ableton, the MPC software is duplication with a nice controller for a hefty price tag. I wouldnt have paid full price I dont think. I dont think the software breaks any new ground.
I'm still having some midi mapping issues, might have to bring in my old midi patchbay to handle it. The software is definitely lacking, but they've already made some decent updates so I'm hopeful.