I don't even know what "concert pitch" is, but I have always tuned by ear, in fact, find electronic tuning a total cock-up where NOTHING sounds right. Since I play with a amateurs, many of whom are all over the place, being able to quickly tune by ear to their instruments is a big help. Also, since my own voice is low, when playing solo I tune down a bit...have no idea how much, just enough to put me in range of the songs I like to sing. But that means lots of retuning when I play with others.