I forgot to mention that it is easier and quicker for us to program around a single motor/encoder (with a gear assembly) than it is for us to program pneumatics (ive done it before and it was one of the most miserable experiences I have had with programming).

Pneumatics and electromagnetic solenoids have already been considered and discounted. According to what I have been told by others, the problem with pneumatics is that it is imprecise (as you have mentioned) and we need precision for a game such as pool. The other problem is that we are reaching the end of our budget and after we get our steel parts machined and our plastic parts manufactured, we wont be able to buy many more components. In addition, there is a time delay with filling the tanks off of the air compressor and in reality, we wont have much time to continually fill and refill the tanks to maintain pressure, plus it makes too much noise - we want the robot to interfere with its opponent as little as possible. As I have probably peaked your curiosity with the E/M solenoids, I will address that as well. We had two challenges with them: power consumption and electromagnetic interference. While we could shield them, our electronics are two expensive to risk on some "half-baked" shielding. On a side note, I am surprised that I have not been notified of your above comment, sorry for the delay.

Have you thought about pneumatics? Great power in a small package, excellent for linear motion... you might not get perfect control without pretty decent valving and instrumentation, but it might be a good option for the next prototype.