I don't see much of a con to a multi pin sight, unless you plan on shooting 3D or long distances. The cons I see to a single pin sight and hunting is trying to adjust it and get the shot off in time.
With that being said, you could always go with the best of both worlds and get a multi pin slider, like Spot Hogg makes. There is also the G5 sight that has several fixed pins and one adjustable floater pin for longer distances. I just ordered a Spot Hogg Tommy Hogg with a three pin head. That will allow me a 30, 40, and 50 yard pin, as well as the flexibility of a slider sight for shooting those longer distances.