Bill, are you sure that you're melting the Grande sufficiently? Grande needs to bubble well, brown a bit and oil off in order to reveal it's true potential. In order to really bubble it appropriately, this means:
A thin thickness factor (no higher than .08)
A fine shred (no chunks/slices)
Room temp or warmer sauce
Slightly warmer than fridge temp cheese
Not too much sauce (you should see the skin through the sauce)
Not too much cheese (full coverage, but not much more than that)
Sufficient top heat to brown the rim a bit
I've actually had major issues getting good cheese bubbling with my traditionally pale-ish rims. Heating the sauce helps a bit, but I have to be careful not to cook the sauce in the microwave.
One or two of the legendary NY pizzerias do use a provolone blend, but I think the majority use straight whole milk. Part skim blends are good for pepperoni pies, as the combination of the fat from the pepperoni and the fat from the whole milk tends to be overkill. Part skim blends are also more cost effective, because you end up with more milk solids, so less cheese goes further. As far as part skim melting or tasting better than WM, that's not something I've ever seen.