[buildmaster5000]

Conceptually, the first thing to realize is that, without encoders, you are just setting a 'speed' value. You don't actually KNOW what speed the wheels are turning. The teams that you talked to really just used PID to control the actual speed (in rev/min) of the wheels. The first step is to figure out what speed you actually want the wheels to be going, then implement PID to get the wheel to that speed.