The ambi safeties invariably have competition style tabs (correctly called the "thumb piece"), which are, as you say, easy to nudge. The original GI safety was easy to operate intentionally, and very unlikely to be "snicked off" accidentally, especially when correctly fitted. The designer of the Detonics pistol would reshape the safety tab to GI configuration on every Detonics that he could get his hands on after he licensed it. Why Colt changed the shape on the commercial pistol in 1949 is a mystery.
I used big, wide thumb safeties for a long time, but after finding a supply of WWII GI safeties, I found I preferred the tiny tab. Jim Hoag put Swensen ambi safeties on all his guns, and it stuck.