My MI BUIS work great with my 512. Perfect co-witness and open field of view. However, I do plan on getting a 553 or 555, both have lower 1/3 co-witness, which gives an even better FOV. The ARMS throw levers are a nice touch as well.These are two popular selections it seems. I have the MIs and am thinking about getting the Eotech. Can anyone tell me how well the MI BUIS line up (co-witness) with the Eotech? Thank you.