Before I start, let me just say that I run a PD stator plate on my bike.
The theory behind the offset key is not too bad; as we all know, it is the taper and proper torque on the nut that holds the flywheel in position, and the key is just supposed to index the flywheel blah blah. I fully agree with that.
However, if the $15 key interferes with the fit and the required "push-up" of the flywheel onto the shaft, then shit's gonna happen.
We have been using a taper fit for our key-less propellers in 100 000HP applications for at least the last 20 years on our container ships.
I say, index the flywheel using a protractor and leave the key out, IF (and that's a big IF), the tapers are correct and matched, the "push-up" of the flywheel onto the shaft will keep the flywheel in the correct position.
Fire at will! hehehe