This has been covered a couple of times already and what matters with the Roku is where your "Roku Account" is homed.
I tried creating myself a new Canadian roku account to compare the difference but since I was using unblock-us it created a US one. And hence they offer me all of the US channels (aka applications) such as Amazon VOD, Vudu, Pandora, etc.
So to conclude: I think you could run out to London Drugs or somewhere right now and buy a Canadian Roku. Then create a US homed Roku account from your computer simply by using unotelly. Then when you link the device to your account you will be offered all of the US channels and contents.
But I can't say for absolute certainty since I bought all 3 of my Roku's in the US and I created my account using unblock-us not unotelly (and I'm just assuming they would act the same).