In my opinion very few solo canoes paddle well Canadian Style (heeled over with both knees in one side of the bilge). In general, as the boats become faster and have a finer entry, this situation is magnified. I own four solos, and only my Mad River Guide paddles well Canadian Style. The rest paddle much better level, and then heeled only to turn. If I paddle a tandem, I will almost always slide over to the rail and narrow the boat creating a narrower, deeper profile to the water all the time. This narrower deeper profile generally creates a hull with less wetted surface, and hence, the boat is often faster, however it is more susceptible to wind. Boats built like the Autumn Mist, and as Kim stated the Bell Magic, all the Wenonah boats, and the Souris River Tranquility, and others, is that these boats already present a narrow, deeper profile, so heeling over is not necessary.
Another bar discussion. The solo boats that I have paddled that paddle well when heeled a little Canadian style seem to be the ones whose stems still are in the water for their flat-boat waterline length. The ones whose stems are out of the water now are in reality shorter boats, and that is not always a good thing if you are trying to make speed.
In a solo boat it shouldnt be "necessary" to paddle Canadian style as the prpose of a solo boat is to make it easier for you to reach the water on both sides of the boat. But "necessary" isnt the same as "I'd like to paddle that way cause I feel like it!".