I recently purchased the Hammock Seat and I must say that it's pricey but I think it's worth it.  I am loving the comfort, ease of setup and the portability of this thing.  It weighs next to nothing but it holds all 235lbs of me with no problem.  I have a new Super Elite III vest that I just got on sale and now I'm thinking I will leave the SE III seat cushion at home and just wear the vest and sit in my hammock seat.

  Hammock Seat