In my case, I had never used SF for anything, but the sellers had an existing policy. Amazingly, SF charged me less than the prior owners by about $700.
SF also required fewer hoops. Nationwide give me a bunch of tasks like taking lots of photos of the property, installing a burglar alarm etc. Try and burgle the fire-prone fringes of East County and your life expectancy is going to be pretty low.
My process of switching everything to SF is now underway. My office rental liability policy was $520 v $550 before, and workers comp for my business appears to be exactly the same as my existing policy.