I really wanted an ultra low mount when I first started playing with the scorpion. I finally bought a Vortex sparc2, which would Co-witness with the iron sights: I hated it. I had to push my face so low into the stock that I lost some field if view and, therefore, some situational awareness.
I installed one of the spacers to bring the sight up a bit and was a whole lot happier. True that I can't use the irons and a little bummed about that, but I think it's quite a bit better.
Same here. After attending a rifle class where the combat-experienced instructor let me borrow his rifle with an Eotech on a riser, I've been converted. I understand the concerns that people have about the optic sitting high above the barrel. But even if it's four inches over the barrel, that's not going to cause you to aim over someone's head at 10 yards. And what you gain in increased situational awareness (not to mention being and to "drop" your head down to the iron sights below your red dot) makes it a worthwhile tradeoff.
Also, if you're considering this and are confused (as I was) on how to zero the gun, get the Applied Ballistics app, go to a range that has a chrono, enter your barrel length, ballistic coefficient of the bullet you're shooting, twist rate, etc. into the app, and it will tell you your custom zero range and holdover for every yard out to 100 yards and then for every five yards out into infinity.
I had a hard time wrapping my brain around this stuff at first, so if anyone wants me to clarify (or maybe I'm the only one who didn't get it and you're all already familiar with it) just say the word.
