The latest version is OS2. But you have to buy OS1 first for $30. Or actually you can download both, but you won't be able to save anything, and it still allows you to fully demo it, before paying for it.
I just got my MPC a few days ago, and I really wasn't feeling the way the sample editing, and more-so the chopping was with the akai os.
I downloaded the free JJOS and IMMEDIATELY noticed an improvement in the chopping function, among other functions.
It's free and you can always erase it and go back to the factory defaults if you're not feeling it... but I doubt you won't.. it's impossible for someone not to, because it's something akai should've done themselves and should be ashamed that someone else could get there machine working better than they themselves offer to do.
