You should never mount a plastic sight on a gas block to begin with . or meltdown should be expected
I've tried it both ways with a holosight.
My preference is absolute co-witness.
I dunno. It just "feels" right to me.
The nation that will insist on drawing a broad line of demarcation between the fighting man and the thinking man is liable to find its fighting done by fools and its thinking done by cowards.
Absolute Co witness for me.. always.