I have never noticed any difference between Canadian and US customers, but I do get people from all over asking me to mark the customs form "gift," which I don't. OTOH, I always mark a minimal amount for the value; that's mostly out of laziness on my part, though--I just don't want to look up the order amount. I have had customers from the UK rank me out when I put the regular value or when customs there opened the package and they had to pay duty, which was a LOT, like a third of the cost or something. A few customers there have actually demanded that I put that they would have to pay duty and how much etc., on the cart. Right.
We've always flatly refused to put anything on a customs form other than the truth.
We show customers in Canada & Europe pricing in their native currency as well as what their duty, customs and shipping charges will be. A third party handles the currency exchange and logistics for us.
We ship the orders to a warehouse in New Jersey, and they take care of getting it to its final destination.