Good idea. Except that the PA at the Prince is naff. The speakers, for some reason, go over the heads of the crowd, leaving only subwoofers under the stage. Which is OK for booty-pumpin' dance grooves, but not for anything you're meant to listen (as opposed to dance) to.
I really don't think that audience chatter will be much of a problem, since that Mogwai have basically said they expect the audience to bring earplugs. (They even say so on the door to avert OHS issues.) Anyway, the idea of coming down again is tempting...
After all I have heard of Mogwai performances I think you should bring your ear plugs. Apparently they create a wall of sound no audience chatter will ever permeate.