If you're looking for a real light weight inflatable, how about Outcast's OSG Commander at 35# or Dave Scadden's Assault at about 25#, compared to this NRS boat at 51#.

NRS makes top quality boats, but in the video this one looked a bit tippy even on still water (even with its rigid floor you probably wouldn't want to stand up to fish from it in many instances).

Personally, I would feel more comfortable with a small pontoon than with this kayak for both still and moving waters (perhaps an Outcast PAC 9 Featherlight, for example, at just 45#).