I was not meaning to suggest that AR performs better on glass, rather that AR coated glass performs the same as AR coated sapphire as for scratch resistance -- and even better as for crash resistance. About possible differences in the AR effect yes, I'd have to compare like you say.
I also remember your note about AR coating on glass not getting the same blue tone as on sapphire, chief. But that guy asked for double AR coat on a PAM, so he does not look excessively concerned about accuracy, rather about overall look.
And, frankly, I personally find colorless double AR much better looking than blue single AR.
Well, even better than blue double AR to tell the truth.
To me, double AR should have the crystal like disappearing. That is voided by a blue tint (that, even more, modifies the color and look of the dial).
Naturally, if we otherwise speak about accuracy, that's an entirely different matter... On PAMs, at least.