Rob,

The sled you refer to was built by Robbie Stewart of Dean River fame.  I'm not a sled builder but in general the weight factors of stitch and glue versus frame built at quite close.  S&G looses the frames but adds a great amount of epoxy resin which easily makes up for the weight of frames.  Both methods are tried and true and will produce a fine boat.  Each has it's fans and detractors.  I prefer framed boats because I'm a traditional kind of guy but there is nothing wrong with other techniques.