I would say that if you want to pick up the tapping sound of the dancers, you should use a boundary mic (either a PCC or a PZMmicrophone will work fine). As far as a shotgun mic (and by unipoint, I'm assuming you mean hypercardioid or shotgun), I don't think they would work quite as well as a boundary mic simply because the sound has to be more focused in the microphone's direction (as compared to a boundary mic, which uses the surface that the mic is on to enhance the sound), and the microphone can't pick up the low frequency sound created by the tapping on the floor. However, if you use a boundary mic, be sure to place it correctly. See this guide for more details.
Maybe I've been too close to the front at recitals all these years, but I suggest (c) no microphone, especially if there are several dancers. Metal on wood carries well. (I always thought that the footwork was the most important part and the tapping sound an ornamentation.)
But if you still need to have a microphone on the dancer(s), remember that the dancer(s) will probably need to hear the music she (they? he?) is dancing to; that she'll (they'll) be moving all over the stage – up, down, left, right; and that with some heel-toe combinations, the heel will be a pound not a tap.