It will take time to become well versed in the No Peep use but as I understand it when shooting dowhhill or uphill we tend to change our draw enough to make the difference because of the angle. The No Peep is supposed to prevent this since it would show your inconsistency. You would have to draw to the wall to align the NO Peep properly.

I usually draw to the wall anyway but on treestand shots I have taken, I am almost certain that I was not at the wall.

I' m also looking forward to low light shooting oportunities.