I have no personal experience with SFA, and I'm thankful for it. I only know what the teachers in district level committee meetings have told me about it; some of the schools in my district have used it.
They were frustrated and angry; they said SFA was too "scripted and scheduled," did not allow for appropriate differentiation, and that they felt like "Stepford teachers."
A quote from one principal in my district: "I expect you all to coordinate your schedules and make sure you are staying on track. When I walk down the hallway, I'd better hear every class doing the same thing at the same time."
I don't know if this is inherent in SFA, or just a misuse/abuse, but I'll say it again: no thanks!