In any Real Estate Transaction, an agent has certain duties and responsibilities to their client. When an agent becomes a dual agent (if the parties agree) he/she will have inside information from both sides. This is information that he can not share with the other party and so if you are anticipating gaining an advantage from that - it will not happen. In fact most agents are extra carful in these cases so that one side does not get the impression that the agent is working harder for the other side. Some times, in my opinion, Instead of leading the way in negotiations, the agent becomes more of a messenger.
The main advantage is control of the process. Your agent will not have to worry about having an under preforming/non responsive agent on the other side (hopefully!) and it usually makes for a smoother deal.
There is nothing wrong with these types of deals if you are so inclined but I would recommend that before you commit to the agent that you consult with him/her. If you are not comfortable then advise the agent that you are going to seek out your own agent for representation, I dont believe this would hurt your chances one way or the other as some agents dont want to represent both sides because of the potential liability.Good Luck.