To me, riding SS is the Zen of mountain biking. It's simple and yet more complicated than riding gears and there in lies the challenge. There is more strategy in singlespeeding when it comes to attacking the next climb, or if you are riding rigid, picking the next line. Never heard the wrong gear bit but I like the false bravado of One Gear = More Beer!
Don't go full sus on singlespeed, I think that makes you a pussy. Do the opposite, ride rigid!