Exclusive Query letters

We all want the greatest chance of getting an agent. Do exclusive queries really make agents pay more attention to us? In one way they are worse because we have to wait. But at the same time patience is everything in the publishing world. The other way if this is a reputable agency that you really want to land then maybe its worth the wait...Personally I sent out one exclusive query letter and am still waiting for a reply. The only reason I took that step was because the agent is surely reputable and because they are looking for a novel just like mine. How about you, what is your take on exclusive  query letters?