The Nucanoe looks pretty nice. Might see if the local dealer will let you try it out and see first hand for yourself if it will work for you.
Have you looked at the Wilderness Systems Commander 120? I bought one last summer and love it. It's light enough I can throw it on my shoulder and carry to/from the truck and it has a pontoon hull that makes it more stable allowing you to stand and fish. I've even stood and paddled down river in it once in mild rapids on Elk to see what it would do and it did just fine. Still I mostly fish sitting down, but its nice to be able to stand if you want (especially when I have to retrieve lures from the trees). It also has 2 seat positions, so when I get tired I can move up to the captain's perch which makes it feel like a canoe. It's agile enough that I can work my way upstream and float back down if we aren't able to shuttle.
I bought mine from riverjim.com in Buffalo, MO where I could try out several different kayaks there on site and the Commander was by far my pick but he didn't have the Nucanoe to compare against. Not sure if he still does it, but when I bought mine he was taking 20% off MSRP.
Like others mentioned though, a narrow 16ft Jon boat is hard to beat, especially if standing is your main goal. Just depends on what waters you are fishing if its practical or not.