Zero with a gearbox
My impression has always been that the direct drive Enertia and Empulse concept were Brian's, and the IET gearbox was Craig's. The race bikes were certainly Brian's lovechild.
There are some valid engineering (and non-engineering) reasons for a gearbox, which Brian did tout when given the opportunity. And costs as well.
Regarding the motor - should be relatively easy to rebuild the motor for a higher or lower voltage. Harder issue will be going higher voltage on the battery pack - though the "long brick" design should allow 56S1P instead of 28S2P for 196V - 235V.. that's maybe worthy of separate discussion.