I've seen this utter horse crap posted many times, and recommended by tyre fitters.
as long as the tyres are over 3mm tread, they will perform to the same. In the dry grip will be the same.
Even under 3mm as the grip starts to degrade, the difference in grip (in the dry) is negligible.
if you're driving on the road to the point that the car is losing grip at either end, then the electronics will take care of it.
if you turn the electronics off, then the R is very predictable and forgiving.
i rotate the tyres on the wife's at every seasonal tyre change, to get the best life from the tyres, and then replace 4 at once.
my 911 (and the previous 1) had different sizes front and rear, and I never found any odd handling characteristics, with rears at 2mm and fronts at 8, or vice verse. Rears last 8k, fronts 30k+ so impossible to have similar tread depth front/rear for any length of time.
my track car runs the more worn pair on the back and the better pair on the front. Mostly because the front munches them quicker, and ao48s are not cheap so done to get best possible life. Again I've never noticed it make any difference from a grip perspective.