IRON LYONS Team 912 - Canadian Regional Champions (this was the 2nd-annual Canadian Regional) along with rookie Canadian team 1088 S. W. A. T. T. and Delphi-sponsored 378 The Circuit Stompers.
Our robot, S. D. L., does not support any gear-shifting; we had our motors set to low gear all throughout.
I think it was more the strategy of our alliance's robot combination that took us to the top. 378's was one of those that could be classified as fast and compact; it went up the ramp in autonomous real fast and real smooth, spanning the entire width. 1088's was a slow-moving ultra-torque-&-traction-loaded brick that could bully any bot it wanted to. 912's (ours) was a mediocre bot that had pretty decent torque and speed that could stack, re-orient, and bulldoze with a front-arm that goes down.
378 was reliable for autonomous, 1088 was reliable for king-of-the-hill, and 912's bot partnered up with our skilled driver, made it strategic in both offensive and defensive play.
The rule of thumb, therefore, I suppose, is to have a combination alliance consisting of slow, mediocre (but ability to multi-task), and fast robots. (one of each type).
Verdict: No need for gear-shifting!

Although I think 378 had support for it, they were always menacing around in top-speed, so I don't believe they ever used it much.