I have tried just about all of the above. My problem is that I am right handed and left eye dominent, so I close my left eye ( or squint really tight ) and that does not work with a lot of these systems. After spending a ton of $$ on glasses, contacts, etc. what I have done is:
for iron sights I have gone to a wider opening on the rear sight and a fiber optic ( small ) on the front sight. The bigger opening on the rear helps a bunch.
for USPSA I have gone to OPEN with a C-more red dot. I really like my red dot...works with an AIMPOINT on my carbine also.
hope this helps,
George