I have had a few customers in the past that wanted both a scope and holographic red dot sights mounted on their rifle (usually AR-15's).
I've always offered 2 configurations, either the holo-site is mounted ON TOP of the scope, or a 45degree offset base is mounted under the scope so the holo-site is mounted to the side at an angle (right side) of the scope.
I like the 12 o'clock position above the scope because it doesn't require the rifle to be shifted from a natural shooting position, but it DOES take the head out of position on the stock. The 2 o'clock position requires a bit of a tilt to the rifle from normal shooting position, but it keeps the cheek firmly welded to the stock.
These were typically rifles meant for "tactical" use, but I'm using a similar set up for my 6.8mm SPC AR-15 for deer and coyote hunting. I want to upgrade to a higher power scope like a 8-32x50mm and then use the holo-site for short range shots (sub-75yrds).
Any opinions on which is a better position for the complimentary holo-site? 12 o'clock HIGH, or 2 o'clock? Is there something I'm leaving out?