I all of the mail line classes that I have attended, only one school recommends the slide stop. The only benefit to using the slide stop is speed, if all goes well. The down side is that slide stops are small and you could fumble it.
And your hand could slip on the slide and you could fumble that too. I find it a lot easier to slip on a flat slide than on an angled slide stop.
If the gun is a battle pick up, you may not press it at all.
You know, the reality is that most likely none of us will ever get in a gunfight. If we do get in a gunfight, it is unlikely that we will have to reload. The chances of us getting in a gunfight where 1) there is another gun we could pick up, 2) we actually run out of ammo on our primary, 3) we are able to pick up that other gun, 4) we run out of ammo on that pick up gun, and 5) we also picked up a spare magazine for that gun is so
infinitesimally small as to be non-existent! I am not going to give up 1/2 second on my reload for that possibility and I suggest that you reconsider the odds if you are actually using that as justification.
Oh, and btw, you better hope that your battlefield pick up is not a 1911 with a shockbuff in it, because overhand won't work from slide lock.
The two surest ways are methods #2 and #3, although I prefer #3, because it is the way that I rack the slide. Someone asked about the difference between fine and gross motor skills. The easiest way to explain is to think of them as "Dexterity = Fine" and "Strength = Gross".
You have offered absolutely no proof that 1) cycling the slide is easier than thumbing the slide stop, or that 2) it is less likely to be messed up under stress, or that 3) it is actually a fine motor skill rather than a gross motor skill. Once again, all you have done is to repeat the assertion that cycling the slide is somehow less error prone than thumbing the slide stop. This is what always happens in this discussion -- the proponents just repeat that it is less fumble prone without providing any proof whatsoever of that assertion.
As to your definition of dexterity versus strength, sorry but you'll have to be a lot more specific about why one is dexterity and the other is strength to convince me. Seeing as none of us here is an expert in the physiology of hands, I doubt that any of us is qualified to say what is and what is not "dexterity."
BTW, we only teach the #3 method.
Then you are seriously short-changing your students. You should do what Ayoob does -- teach them both methods, discuss their pros and cons, give the students your recommendation, and let them make up their own minds. I respect instructors who teach me all the options and trust me as an adult to decide what works for me.