[thatprogrammer]

Here's an additional thing you may not have considered. Many teams use steering wheels and arcade drive in order to have very smooth, continuous turns and prevent the driver from "jerking" while changing direction and slowing down acceleration. This lack of stopping while changing direction means that you keep accelerating, which, depending on your gearing, could save you a vital second or 2 if you are doing a full field run!
My team hasn't ever tried this, but we are considering trying it out after talking to 1678 and 971 at world's who seemed to like it very much. Austin Schuh from 971 is probably the best guy to talk to about this if you'd like more information on how they do it.
More important than whatever drive system you use is that your driver gets PLENTY of time to practice. Allow your driver to use the same system again and again until they can smoothly do anything on the field without being confused or not doing what they want in a smooth manner. The enemy of an efficient driver is an inability to do what they desire easily.