Just my opinion, but GET THE MECANUM WHEELS OFF!

I know the omnidirectional drive is cool, and looks promising, Any standard tank drive system will easily push you all match long. I think mecanums are cool for any purpose other than competition. Do you know how many mecanums usually make it to Einstein? As far as I know, none. Any team with mecanums are not only easily pushed, but are generally easily defended against, which, while game pending, is never a fun thing.

I think mecanums are just a waste of weight, and drivetrain, so that is my advice to you.

EDIT: Also, it looks a little back heavy. How's the weight balance working out for you?