Howdy Again
For what it's worth, I always shoot a single action revolver with my pinky under the grip. Always.
Here is something you may not be aware of. If you have average sized hands, and try to cram your entire hand onto the grip, the knuckle of your middle finger will be directly behind the trigger guard. Fire a round with much recoil and the trigger guard will most likely whack your knuckle in recoil. Not very pleasant. By only wrapping two fingers around the grip, and curling my knuckle under the grip, this automatically adds about 1/4" of space between the knuckle of my middle finger and the rear of the trigger guard. Try it and you will see.
I shoot nothing but full house Black Powder loads in my one Uberti Cattleman and a couple of Colt 2nd Gen SAAs. These loads deliver a pretty stout recoil. I do not hold the gun with a death grip, in fact I hold it pretty lightly. When it fires, the grip rotates a bit in my hand, my pinky stops the rotation, and the gun then lifts my entire forearm a bit. I find it is very pleasant to shoot this way. My knuckle never gets whacked, and my pinky does not suffer either.
Try it, you may like it.