Warning! CFD price can be easily manipulated by those brokers (but anyway, Gox does it too). Lot of broker's profits comes from price manipulation, not from spread or commissions
On the other hand, 1broker closed down BTCUSD because of users manipulating prices.
It is legit for the big players to manipulate it; it's not that legit (but still legal) to make wider spreads and kick out traders sooner. NEVER trade with larger spread-brokers, use commission-based brokers only