After reading these comments I dug around and found links to our old GTBs and our GTB2. Here are those links to our various GTB versions:
Early GTB (4-cell version)
GTB / Lipo Cut-Off
GTB2--Current Version
All versions have the same value MOSFETs and low on-resistance. Maybe the early GTB versions, with fixed (factory pre-set) throttle profiles, allowed less "fiddling"/tuning than the new GTB2 with all its options. So, they went faster!
Wouldn't that be ironic?