I'm with DasGuy and Striker1. For irons only, fixed makes the most sense and is the most robust.
I use a MaTech on one of my carbines as a backup sight. The primary sight is a traditional 1-4x scope that pretty much stays on 1x. If something happened to the scope, I think I could rely on the MaTech.
Just for grins, my brother dropped $25 on a cheap NC Star fixed sight that he found on Amazon, thinking he would get a better sight later on. It looks like the rear part of an A3 carry handle. That was 2 years and 5000+ rounds ago. It has worked so well that he sees no reason to replace it. It is starting to look beat up because he carries that rifle everywhere he goes, but it is still holding up.
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