All a bit eye of the beholder, but I feel that my SM is less noisy than a standard gibson type. Havenīt gotten to do a proper comparison though. Main thing might be that a SM is often used under more gain, which means more compression, which in turn also makes hum seem more. But even then....again BKPs are clean. To be fair, most botique makers are fairly clean. Still, I just feel pretty great about these.
Again though, shielding, good power supply, isolated cables, etc. all play more into it with a P90 and such than a HB. Just simple addition in the end.
Bottomline: I am fairly sure you will be fine and get a great dirty rock sound with proper character.