For one, the PJB Flightcase/Headway combination sounds so good that the mic doesn't really add much. For two, the issue I'm having with all mics at the moment is that up to a point, they help your sound. Beyond that point, they make you sound worse. If you set your sound at the beginning and the volume creeps up from other sectors of the bandstand, you're pretty much shagged, baby... at least until you have time to adjust again. With a pickup, you find the best sound you can and just play.
I agree with that very much. It just seems such a hastle to set up and continually adjust a mic. With plug and play you can enjoy the music more.
The only exception, for me, would be if there is a good FOH rig and a competent sound guy. Just give him the lead from the mic and let him do the rest. Then use your pu into back line as a monitor.