I have used the Magpul MSR-4 and HSP convertible 2 pt/1 pt slings on my SBR, which has an 11.5 barrel...I also use Mappul's QD mounting hardware on the MS4 (HSP sling comes with QD hardware)
Run a couple of classes with this set up and not had a QD failure, but thats a small smaple size, and I've never had trully hard use...
For SD in my house, or some other CQ environment, I like the 1 pt version, as it makes changing form right to left easier...when I've carried it in the wilderness, I use the 2 pt almost exclusively, as it is much easier to carry it close and tight to the body while walking. I do not like using a 1 pt with 16" barrel, as it whacks me in the knees (or worse) walking around...
I have no battlefield or combat experience, so I can't speak to that...
NC

