I carry with an open top type holster most of the time so I have had the ambi safety get pushed off many times over the years and prefer the single safety. The trigger is covered so there never were any accidental discharges. When doing weak hand drills it's not hard to learn to push the safety off. My competiton guns all have ambi safeties.
On alot of holsters,custom made too,have the molding done with the safety off,it isn't the easiest to find all the 1911 variations in a blue gun for molding made with the safety up.It's common for an ambi to be knocked off carrying if anything touches your side,happens to alot of people.
Since I'm a righty,I have no use for one.My index finger can swipe it off on the grip if I grab it with the left hand,and if it's being transfered to my left the safety is off already.There's also the issue of the joint loosening.If they are fit correctly with a positive stop for the rt side they're fine,quite a few aren't fit so well.The issue of tension is a great point,I've seen many that come off easy but go on harder.I've had to adjust many of mine,new gun or a replacement.A little finessing of the plunger bearing surface cures it pretty easily and you can set the tansion to what you like.
I've carried Condition 0 a few times not realizing it got knocked off,doesn't make me feel unsafe but some freak right out.The reality is,what's going to happen?Shy of a sear or hammer hooks breaking,it can't go off-you have the equivolent of a Glock at the very least,but technically it's still safer.
I think he meant to say mag release.
Rt handed I think it's arguablly quicker to just trip the slide release after a reload as you reaquire the support hand grip,shooting lefty I slingshot it.I don't think they are made anymore but I never subscribed to the ambi slide release,but HK figured out the mag catch long ago.I'd love to have that incorporated into a 1911,so the best I could do is go out and put a USP Tactical 45 in the family.What a nice friggin piece they are!