[JoshJ]

This is just my two cents:

I would suggest staying away from the Reverse gear unless you want things to get very mechanically complex. Also, by using a reverse gear instead of changing motor direction, you cannot make point-turns, you can only counter-rotate. Think about it: Your wheels in reverse go as fast as your wheels in forward, and as far as I can understand, there would be no way to stop only one side of your bot. Personally, I would go with separate drives, but thats just my opinion.

Also, Henry_222's idea sounds cool, but:
1 drive motor + 4 module rotation motors = 5 total OR....
4 drive motors + 1 module rotation = 5 total <--- I'd go for that, more power to the floor, even if more complex.