Any reason you prefer a flip up? I use the fixed LMT BUIS (the one that is basically the rear sight portion of a carry handle chopped off). I used fixed BUIS and leave it on the large aperture under the idea that If I did actually need the iron sites, murphy would dictate that I would not have time to flip them up.

The Troy's lock in either the Down, or Up position. I too leave the up and locked, at all times. Once you are used to having them in the lower 1/3 of your sight picture, you will not even notice that they are there. In the event of RDS failure, you won't lose any time to put the sight in the up position. Since they are steel and lock in the up position, I don't see any disadvantage to this all steel sight. The advantage is that if you then want to run a scope, you could then fold and lock them into the down position, while still having them on the rail. MHO.