If you can afford an ACOG and you want a quality optic, don't let "experts" talk you into skimping and settling on lesser. Most of the internet warriors haven't experienced more than an Air-Soft version anyway.
Get rid of the FSB, or don't buy a fixed scope. There's no reason to dim expensive, quality optics with a now useless FSB. You can't co-witness through a scope. You're likely going to have to get rid of the rear sight to get the eye relief necessary for an ACOG. You're not going to take that optic off if you have a bad day anyways. Unless you are planning to smash it to pieces with a rock that happens to be handy to get rid of it. Or carry wrenches, or negate the weight savings with even more metal on a QD block, etc.
If what you want are backup sights for piece of mind (see my BCM Recce-16 below), then I recommend just getting rid of the FSB, rear sight and getting the BUIS option on the ACOG. I'll post some pics so you can see how they pair up.
The red chevron is a not an 800m reticle. But then again, the 5.56 is not an 800M rifle... The TA-XXX series reticles are more suited for longer distances. I also have a Trijicon 10X AccuPoint with Triangle reticle on my FNAR. It is not a precision shooting reticle by any means. I am more accurate with the 4X ACOG and TA01NSN reticle.
I still don't think a layman is going to be hammering tacks at 300M, 400M and certainly NOT at 800M with it. But then again, most people who think they are going to routinely shoot an AR with low power optics at those distances are disillusioned.
Hey Jon, that's a good looking, sensible rifle you got there. That looks like another vote for BCM to me...
You cannot see the fine hair BDC reticle in this pic, but it is their. As is an ample amount of amber luminescence lighting up the reticle in the dark.