Interesting, I haven't seen the bass version. For what it's worth, I own the guitar spider capo and use it on my 6 string bass just fine. I will say that it probably wouldn't work so well if you use heavier gauge strings (my heaviest is a .101 E, when I had it strung with a .130 low B the lever was a bit overwhelmed) You probably can't capo higher than the 5th fret due to width but I personally wouldn't need to anyway. From what I just read it looks like the bass version is just wider and maybe has slightly larger string levers.
Setting up the string spacing on the capo is cumbersome but not really a flaw in the product, there's really no other way you could do it and retain its versatility (I switch between using it for guitar and bass). I would say that I do kind of wish you could adjust the height of each lever so that you could get just the right amount of pressure on the string. I find that if I engage the levers fully to where they are completely perpendicular to the fretboard it presses down so hard that it can sharp your note, so usually I have them angled to one side or another to lessen the pressure, but it makes them less stable.
Otherwise it's a very smart product, opens up tuning possibilities without retuning for little money. You can even pretend you're Michael Manring and flip the levers midsong.
