P90X is good, especially if you modify the routines to suit more MMA style workout. Have a punching bag around, perhaps a sandbag. I've done P90X but I modify it a lot to suit more mma explosive strength and speed.
As for results, just watch P90X infomercial. You really don't need us to tell you if it works, just try p90x for a week and you'll begin to see results.
P90x is more for people who are pretty out of shape who want to get into shape, it really doesn't add that much mass if you already workout. Save your money and plan your own routine, its not that hard.