I like my complementary headphone to be a different sound signature also....leaning toward the RS1 at this point....always was a big fan of this can for rock music.
Be careful not to get the current RS-1e. There's a pretty strong consensus on the Grado thread that it's the worst version of the RS-1. I had one and quickly returned it. It sounded so strange I thought something was wrong with it. The GS-1 is a great sounding Grado, in my opinion it's more like earlier versions of the RS-1