Having a mic on the camera is a terrible way to get good sound. You pick up all sorts of noise and moving the microphone around results in different levels and artifacts. The speakers are optimised to sound best to the audience. The mix on stage often sounds awful.

It might be worth considering another option. Have some sort of recorder (think about renting) in a position where the sound is at its best with the microphone pointing at the stage. In the midddle of the audience, preferably on a boom.

If you're just going to have a camera on stage with a mic bolted onto the top... It ain't gonna sound good no matter what mic you have.