I'm certainly not up to date on Part 91 regs, but I do know that when the Canadian airline I fly with is operating in the US, we are restricted to the US regulations. I would suspect it would be the same for a US aircraft operating in Canada. Alot of airlines here have op specs allowing operation at a lower vis for takeoff but you would likely have to apply for it. I don't have any regs to back that up but if you do a google search for the CARS (Canadian Aviation Regulations) you may find your answer. Of course you'll likely need a lawyer to help you read them!!
The good part is that this time of the year the weather is rarely below 2600 RVR anyway!
