I don't want to de-rail the thread.....but
With most modern combat optics the main reason for failure would most likely be electronic. If the lenses aren't smashed or obscured then a co-witness solution is very fast to get back onto target/into engagement than having to fuss with a quick release mount (or worse - screws!) to use your irons.
Even a see-through mount would work better, though I find it hard to transition from the optic to see-throughs....at least in my limited experience. It is better than fussing with a quick detach mount though. In the event the optics get smashed the see-through mount has obvious advantages to the co-witness set up.
Co-witness is the way to go IMHO. Sums up what I was trying to get at. Although that being said, I've seen many photos of modern soldiers having no rear back up sight at all on their rifle, just an optic....so what do I know?