Interesting.
I'm personally pretty darn happy with the stock tones from my MM90 equipped guitars. Early on I experimented with height adjusting the MM90's on my AL MM90. They aren't set up to be adjustable from the factory. After a short time I returned them to the stock setup as I felt that was where they sounded best. I'm -very- fond of the Music Man MM90 pups!
I've got quite a few other makes & models with their own versions of P90's, and each one has it's own personality.
Nothing wrong with experimenting until you're happy...