Yeah there are a lot of little subsets of music communities but would be good if the similar ones can combine forces, especially if it's a general music community. I know Open Mic is different and more for acoustic performance (guitar and microphone) which rules me out of it - at least that's my impression of it.
There are still niches in music though and it would be cool to have different branches organised by one leading group to make it look more professional. E.g. Maybe there can be an Electronic music version of Open Mic (I think @daltono runs that community?) and it's part of the branding...
Don't know, just throwing ideas out there and seeing if great minds can come together to make something work!