I totally disagree Cynthia. The number 3 is, to my mind, the only one who could be put everywhere : in your modern living room, next to your swimming pool, in your grass, in an urban place... I'm not woory at all for my back ! You can get out easily by the side as for anyelse lounge chair. The duo concept is original but doesn't forget practicity.
#2 is the only one which made sense for function ... for me at least. Once sitting on #'1 and 3, I'm not sure how I would get out of them with a bad back.