Personally I like the Holy Diver a bit more then the Nailbomb. Despite the outputcharts it has less oomph then the NB several users stated here, it's beefy in the mids and has a sweeter topend, where the NB is more aggressive, especially in the uppermids and has more (tight) lows. You can roughly say the HD being more 80's metal and the NB more 90's. I think the HD will excell in alder. It will beef up a bolt-on guitar, like the Crawler does in my swampashstrat. The HD provides big fluid solotones. For chordwork is will be a bit politer then the NB. I think the Nailbomb can stretch to all the styles you mention, the HD can nearly do that, maybe it can totally with a good amp. It's just not so trashy as the NB can be. If it was my guitar I choose the HD, but I'm not really a metalplayer. Played some stuff in the past though.