I had a similar issue but found a broker who provides both an 'all in' spread option + low spread and reasonable commission. I think we need to consider the accuracy between the conditions advertised vs. the conditions you can execute on..You do have to weigh up costs when it comes to finding the right broker. Between commission, spreads and swap fees you need to calculate which is the best option for you and the way you trade. It's a bit of a minefield.
these 0% commission brokers work the spread / run a b book on the flow they receive so either way they maximise their profits. An STP / A book model brokerage will just pass the order on to the market, take a commission and have no interest whether you are profitable or not!