First, let me say that I am just a regular Joe (Optometrist by trade) so please go easy on me. I just purchased a Colt 6920 in December and bought a EOtech 557 to put on it. I have noticed in different pictures on similar type weapons different placements of the EOtech. Some all the way forward on flattop, some in more of a mid position Is that because that is what feels comfortable/personal preference or should I be placing it somewhere specific? At this point in time, I mounted mine as far forward as possible and it seems ok to me. But I would appreciate any feedback. Thanks in advance.
People slide them forward because you only really need to be able to see the reticle, and the device takes up less of your fov when moved forward.
Also, it leaves room for bis, NV or magnifiers.
nmsg.
Np man.
Being an optometrist I’m sure I only restated that which had already occured to you anyway. 
I keep my toward the rear. It’s a balance issue