Even though these bikes look screwy---they are very light ---at about 18 lbs. the 1899 pederson was years ahead of other makes.
I test-rode one once: I was riding my bent on a cycle route, the Pedersen guy was coming the other way, he stopped to gape at my bike and I stopped to gape at his. We ended up swapping bikes and riding 20km together.
What I remember of the experience is that the hammock saddle is intensely strange, because it's not fixed and it doesn't give you the feeling of having something solid and stable under you when you push on the pedals hard. I ended up frustrated because I felt I might actually get to like the bike given one week with it, but I only rode it for an hour and while I didn't dislike it, I didn't have an epiphany like when I first rode a bent. It was years ago, and I'm still itching to try a Pedersen bike for a longer period of time. Too bad they're so rare.