Yes, because some of the programming work is set around comparing wheel speeds and adjusting individual motor speeds. So (hopefully) each wheel will have a different motor.
Also, the drive chains would pass through areas already designated for our
gathering system. Not an impossible fix but we need to get away from our standard drive system or change the gathering system.
As a side note a great example of a space saving system is at the top of the page:
http://baxterbombsquad.com/whatisfirst.htm