PL:
Hard shell/solid one man tubes/toons seem like a great idea that is brought back periodically, but can't keep a permanent market. The main issues seem to be high bulk,weight, and cost. The main advantages are durability, and freedom from inflation hassles. The experience with the 60 & 75 was about the same as any pontoon. Seating position was higher than a comparable pontoon and they seem to be a little easier to propel. They would be an advantage if you have frontage on the water because you could jump in and go without going thru assembly/transport procedures. Venture had their own low cost versions:
http://www.cabelas.com/pontoons-venture-vo-modular-6-ft-pontoon-boat-1.shtml None of these types is still being made AFAIK. They are good boats from my experience, but they just don't have enough demand.
Porta
Has anyone used a Hobie Float Cat? It has plastic pontoons instead of inflatable bladders. I am looking for some real world experiences.