Michel,
I can't comment on the suitability of any canoe for use in Scandinavian whitewater, as you and Per have been providing me with info on the whitewater there.
By the way, thanks... I might be back with you on that again soon, as I left a few of the websites you directed me to on a prior work computer
Anyways, Let me comment on my thoughts about the Dumoine. I think that the Dumoine is a great wilderness tripping boat for mixed whitewater/flatwater. So I'd put it in the category with the Old Town Penobscot, and the Mad River Explorer.) But it like all canoes has it's design intentions and inherent limitations, and those are that the asymmetrical stern rocker that makes it track well hangs up in eddies under more playful paddling (ala... MKC). If your interest is in a nice whitewater tripping tandem for a weeklong wildernes trip, I think a compsite Dumo would be great. But personally, I'd ask John for the plans for his Madawaska. It has a little more rocker, and definitely feels more playful, with a little less tracking than the Dumoine. The Madawaska is more like a Mad River Freedom where your wilderness tripping might be a little more river oriented and involve few if any lakes.
Hope that helps...
PK