Yes and no, Darren... While the range definately overlaps, the manner in which they're played is still distinct- I mean, there's a difference between the way Meshuggah uses their 8-strings, even when tuned down into the bass register, and an 8-string bassist would use the instrument, even tuned to the same pitches. In terms of note choice (chords/diads vs. single note lines) tone (clean vs. distorted), picking technique (thumbed vs. picked)... These are some pretty broad generalizations, and you can definaely play a bass like a guitar (i really dig the sound of double stops on the upper strings played through a distorted guitar amp) and a guitar like a bass (slap lines, etc), but the manner in which they're generally played, to my ears, differs.
Doesn't mean I don't agree with you, though.
Here at Jemsite, you can post with icons next to the subject line- maybe have an icon for "multi-stringed guitars" and one for "multi-stringed basses," with a third for both? That way, we can have a general forum for all multi-stringed instruments, while still being able to differentiate at a glance whether we're talking about an instrument used as a "guitar" or as a "bass," or as some new entity?
So, let's try this for forum areas:
-Amplification and Effects
-Theory and Technique
-Players and Bands
And maybe an "Multi-Stringed Instruments: an Introduction" board for newcomers? Although, we could probably just stick that into a topic within the Instruments section, and sticky it...
I'm psyched by this idea... If there's anything I can do to help, let me know.
Edit- added a Recording section. Shannon, you're right, these thigns are some of the trickiest instruments to record due tot heir massive range. Good call, bro.