I think I’ve answered a similar question before with this answer:
http://www.bigagnes.com/Products/SleepingBags
I’m 6ft 7 and size 13 shoe and I can safely say these bags in Long are the biggest I’ve ever kipped in.
I have a down bag and a synthetic bag. The down (Lost Ranger 15) is too warm for all but proper Winter conditions in the UK, but might be a good match for what you’re after.
Coupled with a thick pad (Neoair in Summer, Prolite in Winter) they are incredibly comfy to sleep in, really wide, long and massive footbox.
I got both mine in the US, but there are a few dealers now in the UK, George Fisher in Keswick being one and Webtogs if you want to go online.
I’m sure you know the down / synthetic pros and cons, but for me, down wins if you know you’re in no danger of getting it wet and that you will be able to air the bag when you’re not sleeping in it (if not all that condensation that your warm body has put into it all night, will (in a cold tent) stay there and the next night stop your down from ‘lofting’ (fluffing up and trapping warm air!).
Good luck, Canada in the Winter sounds great!
EDIT: OK so you don’t know the pro and cons!!
Broadly speaking:
Down = lighter, more expensive, takes a wee bit more looking after, useless if wet / damp, longer lifetime and often warmer (if dry and looked after!).
Synthetic = heavier, cheaper, will stay warm even if wet / damp.