I use a harley as well, and have been pretty happy with it. I haven't ever used a preparator, so I don't know if the following would affect them - I was grading a yard and had the drum going too deep. It locked up then blew a seal. I was hoping it could do the whole grading job, short of a final hand raking (which is what the dealer told me it could do), but it looks like it can't. Still need to scarify.