Unfortunately, we never felt completely comfortable with the canoe. It feels extremely tippy and we're always nervous with the kids in the boat. A friend of mine who is a hardcore WW paddler took it out for a spin on the Ottawa River and he too had a very tough time getting a handle on it. I tried soloing once and it was a nightmare. My wife, a more experienced paddler, fared only marginally better.
Paddled solo, the Nahanni performed nicely. The canoe I was using had a kneeling thwart and pads, which were very comfortable. The boat retained the same characteristics as when paddled tandem, and with a little bit of a heel, becomes more maneuverable. It's not a pure sit and switch solo, so you do need to reach a bit on your stoke, and outside of leaning it way over, you won't get a perfectly vertical paddle. But you can't very well fit two people in a Prism, and as a combo tandem/solo flatwater boat the Nahanni seems like a strong option.
Rating: 9/10 - because my girlfriend says it's real pretty
I also own a Swift Kipawa, but it seemingly gets very little use now. I would recommend the Langford boats for cottage, lake, river, & tripping. I also have an ABS Old Town Prospector with wooden gunwhales, a boat to abuse, 'cause the Nahanni is just so darn pretty.