I am a new XD owner, but not new to handguns as I have been shooting for over 40 years now. Usually my preferred auto is a 1911 and in all the years I have been shooting them, I have never had a problem with the grip safety. If I was having troubles it was related to ammo or limp wristing after a long day at the range.
Just for grins I checked the pressure it takes to depress the grip safety on my new XD and it is so minimal, that I can't imagine a situation where you would be unable to hang on to the gun and fire it without having enough purchase to push the safety on. Of course, I am sure there are those out there that can come up with some kind of wildly improbable scenario that would include such a thing, but I think it would be pretty far fetched.
As to the so-called issue with the height of the barrel axis, I measured the distance from the centerline of the firing pin indicator on my XD and the centerline of the firing pin on one of my 1911's and they were essentially the same. Maybe that is why I found that I can shoot the XD so well. It feels more like my beloved .45's than the other plastic pistols I have shot.