I use my plectrum for tapping sometimes because you can get it extremely fast and clear. I don't think the plectrum has ever touched my fretboard though... I suppose it depends on how hard to tap the strings. If you try tensing your arm from the bicep down so it shakes/quivers (kind of like playing an arcade game where your finger hovers over the fire button) you can get some serious speed going. This trick only works for pick tapping as opposed to finger tapping. Another benefit of pick tapping is being able to slide from note to note whch can create a nice effects.