Well if it's metal you're playing, then most likely you'll be competing with your guitarist(s) bass frequency. That **** can really piss a bass player off! It can practically negate everything you're doing unless it is mixed well. Meaning, tell your guitar players to roll off bass and even mids a bit, and focus on treble a bit more. That will allow the bass to come through the mix much better and then you'll be able to reduce volume fights between all the musicians. If you can get to that point, then it's all about the sound you want and has very little to do with specific strings for the genre. If I were in a metal band (and I have been in a few years back), I would do what I said above and hope that the guitarists understand, and then I'd put light gauge round wound nickels and tune down if I need to. There's really nothing special to do. It's more about your personal sound coming through the mix without being negated by competing frequencies.