You have to have a darn noisy generator and be anchored awfully close or rafted up to bother anyone.
Having lived full time on moorings and hundreds of nights at anchor, including relatively crowded ones, we have never got a complaint, and that's with an older Onan in an older Hatteras with no sound shield, not to mention various chartered Grand Banks and Mainships. If we know we are going to be running the thing at night (only in the hottest weather) , we make sure to be downwind from others.. not because of noise, but exhaust.
As I've said here before, if we loved a boat that came with a good propane kitchen, or one with an electric kitchen (like the Hatt did), we'd spend 0 dollars changing out appliances either way, though we prefer electric for convenience and safety.