Generally, yes. As far as regulation goes, FCA is one of the best authorities out there. The problem is that regulation does not protect from problems with the broker. Alpari UK was a properly regulated company too.
Best to verify that client funds are held in segregated trust accounts. This does not protect open positions, of course, but if a broker goes down financially you want the liquidators to clearly distinguish between broker funds and client funds held in trust.
Yes, both FCA and FSA are pretty good and reliable, but you shouldn't rely only on regulations. For example I trade with FCA tickmill and FSA Hotforex, though I pay little attention to regulation as their operation history and feedback from traders highlighted some other important trading aspects which they excelled on - like execution and spreads tightness, cheap withdrawals, etc.