Hi Caz, a bit of a decenting voice from me!
My Shuker's have the extra 2 frets like the Kubicki's, but even so I've found that for noodling around at bedroom levels my Digitech bass synth wah, does a good enough job at my attempts at Uptown Funk.
Before buying a 5 string, I would suggest getting a decent bass synth pedal - most have an octave function - rather than a dedicated octave pedal, and try it. If it doesn't do what you want you shouldn't lose money if you move it on.
Remember, it's what works for you.