For some reason, the chapman stick seems to attract bassists more than it does guitarists, keyboard players et al. I never understand why?
I play chapman stick, but I don't relate it to bass playing at all, to me it is melody playing with my right hand whilst accompanying with the left hand (utilising some bass notes) - all tapped with the fingers. Curiously that description sounds like piano playing!
I agree with you that a stick is NOT a bass! Having said that, it can be used to fill the role of bass within a band. I have an interview with Tony Levin, and he states that when he plays stick in a band setting, he only uses the bass strings, he doesn't use the whole thing unless playing solo.
Great instrument, but extremely hard to master in my opinion (eg I'm nowhere near!)