has anyone used this gear drive?

with a chain, set the cam where you want it and time the thing. now go racing and recheck everything. oh wow did it change, retarded the cam centerline and the timing. that won't happen with a gear drive. do or think what you want but a gear drive is the way to go. the only other thing is a belt drive that will keep the engine right but you have to change the belt every year. no maintenance with the gear drive.