This is an ironic thread. Just yesterday I did some tone tests with an SM57 and a Pearl CM2000 because an SM57 alone has never given me the tone I want on a recording. The CM2000 is a cardioid mic with a battery inside it.
I close miced with both mics and placed the SM57 almost in the center of the cone on axis and the CM2000 at the edge of the cone on axis. The clips I made show the difference b/w the SM57 by itself, the CM2000 by itself, and the two mics blended. I only did rhythm tracks because I double tracked everything and there's no way I could hammer out a lead two times perfect.
Here's the link to the clips:
http://www.soundclick.com/bands/default.cfm?bandID=793530
i love that little riff! the drums really bring it to life.
Keep in mind that i'm just using my computer, and i'm not a recording artist.
This should give you an idea of how much better the tone is when you mix a mic with an SM57 though. The tone is not perfect, but you can hear the benefit of the additional mic.