The bass pedal that comes with Rock Band is not the nicest piece of hardware. This weekend I finished a mod I found on rockband.scorehero.com to replace the pedal with a real bass drum pedal. I used a reed relay and magnets from Radio Shack to get the Pearl pedal connected. What an amazing difference! No more leg fatigue and much faster response. I urge anyone who really enjoys drumming on Rock Band to make the change.
I am still in the process of building a switch that will allow me to use both the new pedal and the original at the same time. The schematic here is what I am using. I just need to get it off the breadboard and permanently soldered.