I haven't tried that. I've heard of hard tack, which might be similar. I've carried those scandanavian type dry breads. They are crumbly, but go well with honey or dates or something like that. I'll have to look up Hudson Bay Bread. Most Canadians take a liquified form of bread, similar to Phats, but non-dehydrated.

p.s. I see its not hard tack, which was traditionally carried on ships. It doesn't appear to have originated in Canada. Looks good though. What still gets eaten alot up North is bannock, and for that you just carry the ingredients, mostly flour, plus some salt and soda. I can see how mushers wouldn't have the time to stop and make bannock, so something like Hudsons Bay Bread would be very handy.
http://www.holry.org/essays/baybread.html