I had a fantasy that a picc would allow me to play an octave higher sort of like a real piccolo does for a flute player. But, when I tried one for the first time, I realized that I could not play any higher at all. My chops were just the same as with all of my other trumpets. At the same time, a picc will not go as low as a Bb so there I was stuck with an overall range reduced by an octave rather than increased by an octave. I found it very frustrating and not at all useful to me.
Maybe when my range improves, I'll go back and try one again but something drastic would have to change before I could ever justify buying one.