I agree with Tench 100%. Other things you should note is security of funds. In the fine print of most of the big CFD providers you'll find that you're an unsecured creditor, ie. if they faulter, your funds aren't your funds. I'm sure Opes is still fresh in everyones minds.
Also, from personal experience, I'd look for a DMA (Direct Market Access) provider rather than a Market Maker. The DMA providers tend to have slightly higher commissions (this isn't the rule) but you'll more than make up for that by avoiding the sometimes ridiculous reqoutes or spreads experienced through Market Makers.
