Got 'em all, except Doctor.
3x9 Scope: on 308 JLD for "reach out and touch someone".
Red Dot: One on Shotgun one on ultimak rail on SAR 1
Holo-sight: on Bushy A3 AK
The scope brings it all closer, the red dot and holo both allow one to keep both eyes wide-open and while you can quicly acquire a target, you are also able to see peripherally, honoring any subsequent, or more proximous threat.
The holo is great on the bushy (also) for three gun competition. It is very helpful if you can set the red dot/holo up in such a way as to be able to co-witness the irons. That way you use the proper sight for the situational requirement, and there is no switching of hardware (sighting systems) if your situation changes. Also, if the red dot loses power, loses zero, or gets otherwise maimed, you are instantly ready with the irons.
The scope on the 308 is on a claw mount which allows me to use the irons, as I can sight them by "seeing thru" the scope mount.
I do not use any of these on a handgun for two reasons: I don't compete in that unlimited class, and I tend to carry every handgun I own, in a rotation, and the added mass is not a welcome thing in a carry piece for me.
I hope this one man's perspective is helpful!
SatCong
PS-- What are you hunting? The Holo is great for 'yotes @ 100 meters or longer, the scope is on a bigger gun for a bigger, meaner sort of predator...
