I have no experience of the Ribcraft, but I can definately testify to the smooth ride of the Humber 6.3m.
My back is extreamly sensitive and the ride from the boat came befgore price as far as I was concerned when trying them out earlier this year.
Once I get the boat back feel free to come and try it. Brixham isn't that far, or we could meet half way.
Its all got to go - make me an offer...............
Skype - alexgreig