The best mic I've found for bass guitar is the Beyer-Dynamic M88. Around $300. I know, I know its supposed to be a vocal mic, but what works is what works.
I have switched from the SM57 to a Studio Projects B1 for guitar cabs. It just sounded fuller to me. Anyone else use it? According to studio projects, it takes an spl of up to 132db, and I have not had any problems.