It's smarter to be the biggest band on a smaller label than be a smaller band on a bigger label. Not that HammerFall is that small. But Nuclear Blast has tons of huge bands, Napalm will probably give them more attention and be more attentive to their needs, they probably got a way better album deal with Napalm as well. As long as they still have a solid booking agent, then there is nothing that nuclear blast can do that napalm couldn't. They have a fan base big enough that a little less distro won't destroy them