I currently have a 'shubb' sliding capo on my Vega. It's alright -not great. It's not *that* hard to get used to, but as BanjoRay stated above, it's not as simple as Shubb would have you believe to install either. Probablt the best capo I've ever used on a banjo was a 3/8" stove bolt. Slip it in between the string and the neck just behind the desired fret and voila! Make sure you get one that has a shank wide enough to clear the fret. The thread on the bolt holds the string nicely in place and prevents lateral movement.
Of course, you may ask why I ultimately went for the shubb....... well, so do I.