Thanks to all who replied.
I'm interested in learning this system, but If I don't trust the instrument giving me the slope, then I'd have a problem moving to the next step.
I've always said " I wish you could take a lesson to learn how to read a green". When I read about Aimpoint, I thought it was too good to be true.
Using spirit levels , builders levels and lasers my whole life, I know that a nine inch level would never be trust worthy, to build any thing...