My brother gave me a set of Ernie Ball heavy gauge strings (12-56), so I figured I'd experiment on the Paul since it needs restringing. After swopping the 12 for an 11, I slapped 'em on and tuned it CFBbEbGC, then BbFBbEbGC. Although it's right on the edge of what this instrument wants to take, it sounds extremely cool, so I've busting out some Lamb of God-style groove riffs and Sikth-type wierdness on it all afternoon! Pretty happy with the tension, although the third string (a plain 24) could do with being lighter.
Doubt I'll keep it this way, but it sure is fun!
I tried 12-54's on my LP in B standard, and they just felt too damn big. 11-54 for C standard or B standard and they're happy campers.