My usual answer is...where are all the engine failures with QSUD? How do you explain the good UOA's? That's right, you can't. What the best oil is, we'll never know, but QSUD is certainly one of the better ones!
I guarantee if you use Mobil 1, pppp, QSUD, Edge, Synpower etc, you'll never know the difference in long term durability of any engine.