I weigh about 155, and have never visibly bent the metal on my peacocks, one pair of which I’ve been using steadily since about 2001. :lol: Happily I’ve never put them to the test, either–when I get dumped my feet normally just pop out. If they break, they break . . . I can live with that possibility. Any piece of tack can fail. But I’ve yet to break a stirrup. And I jump off, not slide off . . . haven’t impaled myself yet. 
I’m not saying they’re the safest, but they meet my needs. I have tried the S-shaped ones way back when and was sort of ambivalent about them because for some reason, IIRC, one of them was always getting caught up on my spur strap or my half chaps. I’m sort of also like GM in this one regard–I dislike “funny looking” gear. :lol:
I’ve no objection to the ones that release, either, but this is nothing to do with the OP’s question! :lol: I just have not found mobile or jointed stirrups any more or less comfortable than regular ones.
I do have the ones with the “eye” rotated 90 degrees on my dressage saddles, as they make it easier for me to reclaim a lost stirrup, which only ever happens to me in the dressage saddles. 