I agree with most that has been said, but there are many different kinds of duckies, some very large and raft like and others, quite sleek and more like a hardshell. I started out in a hardshell so I understand their strengths. I also have a number of duckies from a 2 person Tributary, which is great for some stuff, and a couple Aire Force duckies which are really pretty quick and nimble. I have thigh straps and foot pegs and can roll them proficiently. They can never be as quick and nimble as a hard shell, but for class 3/4 they serve the same purpose for me. And my wife and kids can run just about anything in them without the hassles/risk of dealing with a hardshell. Duckies are different animals, but they are not all slow and lumbering.
May the wind be always at your back,
May the sun shine warm upon your face.