Everyone has anecdotes. I know a person who scored a 250 with just FA and doing QBank. He'd annotate into his FA all the questions he encountered where he didn't know the answer, or the reasoning behind the answer.
Then again he also did a boatload of questions.
As was stated, if you're not the type to juggle many books, FA can be sufficient. But you need to bolster it with tons of questions. It's all your personal study style.
I think the general consensus around here though is that if you want ensure you do well you need to at least supplement with a good path book (BRS Path or RR) and a good phys book (BRS Phys).