Head size probably makes a difference
I think so...
My first AR is an old Colt (bought about 35 years ago) with the Colt 3x scope mounted on the handle (no flat tops back then!).
When I bought a few more in recent years, I stuck with the handle mount (got an ACOG on one). If I try to scrunch my big old head behind a scope mounted on a flat top, it's darn uncomfortable.
Never discussed it with my brother, but a few months back I was looking at one of his ARs when he mentioned he was going to have to raise the scope on this flat top as it was darn uncomfortable for him to scrunch down behind it - looks to me if he raises it much, he'll be into carry handle mount height territory!
Apparently his head is as big as mine!?
One size does not fit all, despite what some folks insist.
I also defy 'conventional wisdom' and shoot with one eye closed.
Yeah, I'm constantly told that's just not 'the way', but I'm cross dominant, with the dominant eye suffering from varying pressure. Depending on what day it is (i.e. how much pressure on my eye), my dominant eye changes - probably hour to hour or minute to minute?
With something screwy like that going on with ye olde eyes, I have no confidence in trying to shoot with both eyes open, much as I'd like to.
It's kinda hard to train yourself to shoot with both eyes open when you never know which eye is going to be dominant at the moment.