We been here for 10 months now, and signed for another year at our currently place with no rent increase. I didn't negotiate (our landlord offered us the same rent), but we have the best working relationship with him that I've ever had with a landlord and that's worth it to me. Also he's open to us modifying the property, which is worth something as well — he paid for ceiling fans to be installed and let me build a big garden in the backyard, for example. The place isn't perfect, but for now and especially during SIP, it's great. I expect if and when we move, we will continue to live in Berkeley.
That said, there are distinctive rental markets in SF. The massive 100 unit buildings without rent control are an entirely separate market from say a duplex in the Sunset.