Re: NS Stick or 6 String bass?
Heath, don't know if you made your choice yet, but yesterday I just remembered something about Chris Squire that may solve your issue.
I'm thinking since you have a four string and Stick, getting a six-string bass will just be more overlap in the same bass realm. Try this:
Stick, NS-Stick, retune your 4 string bass to BEAD (Squire has a few of these tuned that way)
Stick, NS-Stick, retune your 4 string in fifths, like Percy Jones/Michael Manring: CGDA
I tried the fifths tuning for a few weeks on my four string, makes some interesting chords, but scalar bass lines become quite a stretch. Fifths tuning can be fun perfoming live if some other bass player is trying to figure out just what in the world instrument are you playing