I had dabbled with this. Put on a nickel E and G with stainless A and D. I met a guy once who used roundwound B, E, A, and D but a flatwound G. If I understand correctly Robert Trujillo uses a nickel B with stainless E, A, D, and G. My stainless A and D where for chords to sound more clearly (had to lower the pick-up in the middle (p-bass) for volume) later switched to a lighter gauge of hybrid. The guy with the flatwound G did it to reduce string noise when sliding with his rough hands. Has anyone else tried anything like this? I would like to hear what kind of results you guys have had.