I almost never use the pick-up in my guitar (an early Fishman) mainly because I like the sound of an acoustic guitar and the closest amplified thing to that is a good mic. I use a Beta57 or whatever the house provides. The first time I saw Doc Watson he was playing into a mic and I fell in love with his sound. A few years later I saw him playing through a pick-up and it sounded like he was playing an electric guitar. Unless you have a REALLY good sound man, piezo pick-ups can sound really "quacky". I think people have come to accept this acoustic/electric sound, maybe thanks to the Unplugged shows.
I often switch between guitar, banjo maand other instruments and the mic works just fine.

That said, I play with other acoustic instruments. If I were playing with drums and electric instruments, I might just go the Acoustic/electric route.