Right, if they go bankrupt there is no way to know when. My bigger concern is that they don't simply shut down and run away, but then again if they decide to do so there is no way of knowing when. I think it takes time to develop trust in your broker. Even if they are insured, if they run it will be a lengthy process to recover your funds.
Please tell me if you find a FX broker who actually insured accounts. I am not even sure that is possible as you are trading and this is not a bank account. I think if accounts are insured, traders who lose would file suits attempting to get their lost money back but I could be wrong here.