Re: Trijicon is it top big
I've never seen an IOR, but I was unimpressed with a demo model of the Trijicon that I saw at my local shop/range. Felt like pastic, and the bottom post of the reticle was almost as thick as the mildots on it. I suppose it may not have been an excellent example, but still . . .
However, I've never looked through an ACOG that I wasn't impressed with, so take that as you will.
Reticle-wise, I'd say IOR. I love that MP-8. I just "pulled the trigger" on an SS 3-9x42 for my AR, and the only thing that kept me from getting the IOR 2.5-10x42 was the price. College/life ain't cheap these days!