I'd find out the bullet path for the cartridge of the firearm you are shooting -- it will always be an arc (although some are a flatter trajectory than others). Most ammo manufacturers offer this ballistic path information about their products on the internet. Many will cross the "zero" at say 25 yards and a 100 yards --with below zero before and after and above zero in-between. Start sighting in at the closer cross of zero to get a rough adjustment -- then, when you are satisfied with the group -- shoot at the farther distance where the bullet crosses zero to fine tune adjustments.
If your EoTech is used on say an AR-15 with back-up iron sights, the irons sights and the dot on the EoTech should "co-witness" if it is mounted on the same plane as the iron sights. That way, if your EoTech goes down -- you can transition to the iron sights and still get good hits.
After looking at the sightmark magnifier I realize I have to get a quad rail front grip so I can have room for it. Anyone have an extra quad rail lying around?
Way ahead of you. Already sent him a pm. This is a vicious cycle, just when you think you have your rifle the way you want it, you have to get more!!!! Does this ever end?