I was only there for the main purpose which was the story line. Other then that I have yet to go back there, but I do plan on it when I finish the side missions (if & when they get fixed).
Founder of - Banana Republic - Xbox 360
You can get keycodes from the events though - I've been building them up slowly farming bulwarks. I can't recall the name of the two I'm doing, but one was where you have to deactivate, hack then reactivate turrets and hold a position, then the one with the two bulwarks south of that where you just disable two things and mop up the soldiers.
Currently I'm side mission sweeping so I'm all over. Since I live in Cali I go down to San Fran all the time in the game. As for being OP there. Not really they just take a little more tactics. Great spots for Sniper Practice. As for Mutants swarming you for no reason. lol Your not a Mutant that's reason enough. San Fran is also great place for getting big air in Duni's and on Runners.