Hi Saphin,
I'm not sure about AC markets as I haven't used them, but I can say that it's true that brokers will slip you on occasions. It's also possible that some market makers will give you different prices than the market or try to trip your stops.

In the end it all depends if the market maker is holding the other side of your transaction or immediately hedging it. If the MM is hedging it they will want to keep you as a client making big trades, if not they will just want to take your money and close you down.

However, it is important to note that many times market makers can't profit just from the fixed spread and they have to make a few extra pips by filling you a few pips away from the market..

As with everything, try them out, and if they try to play funny games move to a different broker. If you like their charts keep a small account with them just for the charts..