Cool looking design. Great idea, looks like it should work well.
I hate to bring this up, but you mentioned using a drill motor. You may want to check <R46> in the rules. It has many parts, but I'd like to call your attention to this section on items specifically prohibited: "Electric motors different from, or in addition to, those in the Kit, with the exception of those specifically permitted by Rule <R45>." <R45> basically sets limits to how many extra KOP motors you can use.
<R38> seems to indicate this is an attempt to keep the robots on the same power level. However I seem to recall seeing some robots with drills powering parts at competition last year. I didn't look very closely at the time to see if they were modified to use KOP motors. There are some whitepapers describing how that's done. For example:
http://www.chiefdelphi.com/media/papers/1592