Grunt, I meant exactly what I said about twisting...when I shoot my HK91, it stays basically on target. When I shoot my M1A, it twists away from the aimpoint and I have to bring it back around. And the recoil most certainly IS worse than MY HK91...noticably harder. Of course, my HK91 and AR10 are heavier than the M1A, which is a positive for the M1A.
As for your comments on the 91 and FAL's safeties, I totally disagree. I find them easy to operate. I also find the mag release on the HK easy to operate and the stock seems fine to me...if the stock is too short for you, you can always get a stock extension or an MSG90 buttstock. Of course those are individual things, based on finger length, arm length, etc...
I don't find the trigger on the 91 to be that bad...not as good as the M1A but by no means unmanagable.
There are many spare parts available for FALs, M1As and 91s, so I don't believe that is much of an advantage.