You're going to find that people prefer different heights. I initially used the 1/3 cowitness height mount because it was the popular choice and I thought I'd give it a shot. The more I used it, the more I realized that when I shouldered the AR with the proper cheek weld, the dot was in the lower part of the window (the RDS was a little too high for me). In order to center the dot in the window I found myself "floating" my cheek slightly above the stock. Now that I'm using the absolute cowitness height mount, when I have a proper cheek weld, the dot is centered in the window.
Also, just to make sure I wasn't talking out of my ass previously, I looked through my MRO earlier and you CAN see about 1/8" of the top of the folded down front sight (MBUS Pros). It's such a small amount that I really never noticed it before. It's certainly not blocking the view at all.