Fit a Wilson Combat "Bulletproof" thumb safety on a Springfield 1911 yesterday. And by "fit", I mean it dropped in. First time I ever had anything "drop in" on a 1911 that didn't require fitting.
The ergos on this particular Wilson thumb safety are just far more comfortable than any others I've used, especially if you keep your thumb mashed on top of the safety to help manage recoil, like Ken Hackathorn teaches.
Yep that is one reason I love shooting guns with frame safeties. With your thumb up there it really lets you get a tight and high grip on the firearm. After shooting thousands of rounds through my CZ Cuztom, my 1911's, Sig Legion SAO, and X-calibur Grand Power, it becomes second nature. I can tell a difference when I pick up any of my Beretta's with their slide mounted safeties (which I don't car for). I can also tell the difference with some of my striker fired guns, like my P320RX. Just doesn't feel like I am getting my hand as high as I could without my thumb up there for support. However, my Steyr L9A1 has excellent grip ergos for a high and tight grip. Love the gun, just don't care for the grip angle.