I think a bass player is the easiest. (drummer the hardest) I have played keys with 3 or 4 different ones, the only problem is getting one who can follow the time of the keyboard, and not keep turning the beat upside down. My Daughter is the only one that stays in time, (but I trained her since age 7). Also throws you off a bit to hear a different bass line than the style bass line.
Can work great if you get a good one and spend a little time in rehearsal.
(plus'es)
Adds another vocal to your act, someone to enteract with, and gives a more uncanned feeling to your music.
(neg's)
Share the bucks, Doing a solo when no show, and your all set up for two, drinks too much, chases the female customers, etc. etc. etc. etc.................
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