Although I can read....I personally NEVER use any fake books, charts, or any music whatsoever on stage it really holds me back from performing in the manner I want too & shows much better stage presence........
it might sound crazy but I was taught to play with a BLINDFOLD ON as a great exercise to play & sing without looking at the keys or reading music/lyrics.....this will Definitely help anyone once you start doing it song by song, day after day try it sometime....
being a slave to the charts is a big hindrance for a OMB that can be overcome with much practice for sure.....plus it allows your music to breath and gives you the ability to ad-lib, & improvise which makes for some really fantastic sounding musical playing it your way!!
Good Luck