Ah, totally hear you about the boots weighing you down.  I was really worried about this when my wife tipped on little Allagash stream and I had to rescue her and her kayak. Luckily, my dry pants were cinched pretty tight around the boots that my boots stayed mostly dry even though I was in the water for a bit.  I could totally see how this could be an issue if dry pants dont have a tight gasket.  Thanks for the tips!