The BD is defnitely "in between, or even closer to modern". It does Led Zep and Guns'n'Roses soloing very nicely, but feed it gain and it becomes much more modern sounding.
The "vintage hot" solution if you want more "vintage" would be the VHII.
For the OP I think he shouldn't worry, the Nailbomb is a good and versatile choice. It reminds me a lot of Dream Theater (Six degrees of Inner Turbulence through to Black Clouds/Silver Linings). If he wanted more or the solo vibe from Carcass/Arch Enemy, the Miracle Man/Juggernaut do that better.
BD - big, PAF sound that has a lot of mids and is very warm. Best of both worlds. Sounds a lot like the "doubled studio sound of EMGs", i.e. wall of sound.
NB - thinner, raspier and more aggressive, but also tighter and IMO has a great old-school touch to it when not boosted. It will probably be the furthest away from the Carcass rhythm sound though.
MM - Huge metal sound, will definitely handle the lower tunings, but not "vintage". Has really great palm mutes as well. It should be easy to get that Carcass sound with an LP out of it.