I think I might be the "treblish" guy.

Reason being is that I don't have a
universal favorite setting. It entirely depends on the song I'm playing and the bass I've chosen (also, to a lesser degree, which of my favorite players I'm trying to sound like

). I should also point out that my 1x15's tweeter is shut down.
I've got my treble turned waaaay down on my Precision, because I only use that for blues and Motown. With that bass, I'm looking for straight thunder.
In general, I like my bass to growl. I choose my Ric for
growl + high end and my Jazz Bass for
growl + low end.
And metdistortion, with regard to the gain settings, it frustrated me initially, because it sounded so overdriven (at any gain level) it was kinda "muddy". I've since found that turning the "gain boost" off allows for finer control of the distortion. Give that a try and tell me if you find the same thing...