At some point we all have to sack a friend and nobody enjoys it.
I’ve seen this situation a lot. I’m afraid those that don’t have the guts to do it tend to wind up with bands that don’t progress. If you’re having trouble working up the courage, just remember that if you don’t bite the bullet, the frustration will mount over time and increasingly undermine the band dynamic. So the friendship is probably going to suffer further down the line anyway – and the more the longer you let it fester.
You have to do it in a totally reasonable and friendly way – highlight and focus on the issue of different interests and styles, suggest they’d probably be happier with another outfit anyway. Perhaps you could suggest that they’ll be first on the list if you have projects in future that are more “them”.
Above all, stress that it’s not personal. We’re all used to “musical differences” being used as a euphemistic code for “can’t stand each other”, but genuine musical differences do exist. Of course, as I said, if you don’t grasp the nettle early on, the blazing rows will usually follow. It really needn’t be personal, but it will often become so if you avoid the issue for long enough.
You should still be prepared for some hurt feelings though – it’s inevitable.
But I’m afraid the fact that “Bill is such a nice guy and we’ve known each other for years” is never a good argument for keeping Bill in the band if he’s not a good match for your music or just not up to it. Owning the PA or van doesn’t really cut it either…
If it’s primarily a recording band, you can use someone who’s erratic, but sometimes great. However, consistency and reliability are more important than genius for live. Obviously, you’d rather have both, but this isn’t an ideal world. In fact, quite a few bands have different recording and touring lineups. This plays to people’s strengths, and reflects the fact that some people are just more interested in or suited to the studio than the road, and vice versa.
No band members were harmed in the writing of this post.