My first choice would be to use the oak blocks to mount them equidistant from the listening area, and a reasonable distance from the ceiling. Axiom usually recommends about 3 inches of breathing space for the drivers, I think. But, I know of some who have only a couple of inches of space above or below the QS8 drivers, and have no complaints.
However, you are correct that the QS8s are very forgiving regarding placement. Mounting them at different distances from the seating area can, for the most part, be compensated for by setting the correct distances in your receiver's speaker setup menu.
It comes down to doing what you feel comfortable with and find the easiest. I wouldn't be too concerned about going with any of the choices you have available.
