I'm glad it worked out for you. I've looked at T-Mobile's coverage map and there's no way I could get by with T-Mobile based on my travels.
I also tried using T-Mobile, but I could not use it. I am in San Francisco too. It is because my office is in the basement of a building. I get absolutely no service with t-mobile, while ATT and Verizon are completely fine.
I have come to find out that it is because the frequency bands t-mobile uses are not good at penetrating buildings, so I get no service almost as soon as I walk down the stairs. Meanwhile ATT, and Verizon frequencies penetrate buildings quite well.
It's too bad. I would have switched a while ago.