Personally I have never paid any player to rehearse. I think it just gets weird really fast when you set a double standard in a tight band. A band made up of pro studio musicians is a very different story. We prefer to play with keys players and occasionally I brought in a consummate pro for a high paying gig. The core band members will rehearse to develop a groove and the keys player adds color. Give them a song list and lead sheets in the keys you use and they can run with it.
We had a lead singer who came in one night and explained that he WAS the band so we would have to pay him to rehearse and he would take a double cut from every gig. We looked at each other and collectively said: " You are free to leave now." Last I heard he was still in prison.
We had a lead singer who came in one night and explained that he WAS the band so we would have to pay him to rehearse and he would take a double cut from every gig. We looked at each other and collectively said: " You are free to leave now." Last I heard he was still in prison.

Cajundaddy