I'd be avoiding any broker that is heavily involved in margin lending or CFDs unless they are backed by a major bank. You hear murmurs that other major non-bank margin/CFD players have also been struggling with liquidity, and the disaster with Opes is the trigger for other investors to unwind there margin dealings with other companies which will expose this in the near future. Do not be surprised is another half a dozen other financial market players follow Tricom and Opes in the next couple of months (once they can no longer hide their lack of liquidity).
As long as the holdings are CHESS registered and you are not using them as security for a margin loan they should be safe (though don't trust non-bank affiliated ones as they could easily lie to you and transfer your securities without you knowing it if they hit a crisis).
Problem is of course that even if your holdings are CHESS sponsored, you still lose as asset values may collapse.
I think if you are margin lending outside of the umbrella of the big four banks in the current environment you have rocks in your head.
