the 1515 1y is not too much motor for the truck, but it is too much for the mmpro. Go with a MonsterMambaMax. I mean, it'll work, but you risk blowing it. You are way better off with an MMM in a monster truck (that's why brushless revos come with them)
Anything else you could possibly want to know about the e-revo has been told by Mistercrash in this thread:
http://rc-monster.com/forum/showthread.php?t=20864
It's absolutely worth reading it all if you want to learn about your truck.
Peace