I have a one man pontoon (ODC 816) and my father in law has a two man boat like the one you have pictured in the link. While the two man boat is nice because you can stand in it and two people can use it, it is not as practicle as the one man boat. I have floated the Toulmne river several times in both and the the two man is harder to position with fins, which meens that if the water is moving very good at all one person is rowing while the other is fishing. The one man boats are more manuverable and easier to keep still in slow to moderate moving water (good workout for your legs as well). In my opinion the only time where being able to stand is an advantage is when you are sight fishing. Transportation of the one man boats is also much easier, my father in law's boat sticks out of the back of his Longbed full sized pick up and is kind of a pain for two people to put load.

Lotta ins, lotta outs, lotta what have-yous