So I have been away from my bass rig and regular bass because practice was canceled this week, but I tried the Giggity at home last night in abnormal circumstances--that is to say using my girlfriend's Danelectro Longhorn bass (which I quite enjoy playing actually) and Vox practice amp, and then through a Crate Powerblock and Emperor 2x12 guitar cab.
In these instances, the Giggity seemed to amplify the hi-fi nature of the bass, but definitely added fullness, though not necessarily extra low end, even with the "Body" knob up. With that knob increased and the sun-moon dial all the way to moon, things got darker and low middier, but never unpleasant. And again, using the Giggity to drive an ARC Effects Big Green Pi...let's just say I got lost for a few minutes with that combo.
I am reasonably confident it would still sound good through a larger bass rig. It's not an EQ pedal per se, it's more of a tone-shaper with a bit of transparent OD mixed in. I actually keep the Loudness knob (input gain) at about 10 o'clock usually, it can add some harsher sounding gain once you past noon, and then you have to re-EQ everything, and it negates the cool sound you had before. But that's not really a drawback to me, it just is.
So I'd say, if you have the means to try one of these, go for it. Looks like they can be had for $100 used, and you'd get your money back out of it if you didn't like it. It's a permanent staple on my guitar board, and I try to keep effects around that are friendly to both guitar and bass, and would personally consider it to be good for that.