On the PG set, the middle setting (both pickups on), gives a thinner sound, almost Fender like. This is the big difference in his sound and was caused by the magnets being reversed in the neck pickup after it was rewound. There are other differences too, but I am getting a set for a custom built Les Paul (like a Jeff Beck but with a 25.5 in scale). Everyone who has them seems to love them, so I am sure I will like them.
Don't get me wrong with the MQ, they are a very dynamic pickup and respond really well to how hard you play. All P-90's are like that, at lower volumes and attack they are very clean, but when you dig in and turn up, then they drive the amp and really sing. I am a big P-90 fan and can even live with the hum!!