My guitard has a new 7-string axe

[Korladis]

This might be true in some genres, but I'd argue that in metal it's almost mandatory to be able to match the octave beneath the lowest note on the guitar, as it is going to be heavily used. Following the root note is often just going to be most effective path to take for a song.

I'd also say B or lower for the guitars bottom string is pretty much standard in contemporary "mainstream" heavy music. Think Mastodon (down to A I think), High on Fire, Amon Amarth, the majority of death metal and whatever-core bands, all that "Djent" and sludge/postmetal stuff. I'm hard pressed to think of popular "current" bands that don't.

edit: Just realised how old this thread is...

In my doom band, we tune to B, and I do somewhat follow the guitar.

In my black metal band, I don't follow the guitar much, really. The bass part is a separate line. I don't think following the root note is always or even usually the most effective path to take for the song in that band.