Though it sounds like a good idea, the problem I see are newbies, or players with "low" skill. (while low is relative)
They'd be stuck with lights, for the whole game, while a few good ones already field assaults.
I'm not really a pro, but I normaly have KDs of about 17/1, so while it'd be kinda fun for me, my opponents would probably leave after a couple of minutes, because they can't catch up on me only for the fact that I have the bigger mech.
Also, since you recieve your CBills after dieing, the ranks would actually be useless...