Collin:
Sorry I didn't see your post until just now.
S.P.A.M used 4 CIM's, 4 NBD gearboxes, and 4 "half tank treads" last year, and we loved it. We'll probably go with a similar design this year if it fits the game. It's the fastest we've ever assembled our chassis and drive system. The biggest drawback was the cost of 4 Breckoflex belts; they don't get much cheaper even though they are half the length.
side view
top view
Sorry, these are the best pictures I could find on our website. We drove the center sprocket on each tread with the output of the Dewalt gearboxes so we theoretically had 4 wheel control although we just ran them in pairs like a full tank tread. The treads are slightly angled down to the center to give the same "boogie wheel" effect that allows turning without dragging the treads.
We have always build our own custom gearboxes and other than the omniwheel drive system we built in '04 we have always used tank drive, but with 4 identical motors this was the first year we split them up that way. As has been posted, this system seemed more powerful than Fluffy. Credit of course goes to Gary and James Jones (James was a featured presenter on drive trains at the '04 FIRST conferences).