I've been playing a lot of slap pop stuff on the guitar lately - it gives such an orginal tone, with so much variance, that I love it! Can't do it all the time though, cuz my fingers are unfortunately not fast enough for that...

One thing to support buying a bass - you will find many more opportunities as a freelance musician to gig with a bass than a guitar. Guitar is just not needed for a lot of things people are hiring for, or they will already have a guitar player (cuz everybody and their brother plays it). I personally thik the bass has ten times more soul than the guitar does, if soul can be quantitatively be measured.

Or you can just be like Charlie Hunter, and get a custom made $3,000 guitar that has bass and guitar strings on it, with a special fretting system - then you can play both at the same time!