I bought an s8 in HK back in the summer. It's the hong kong version, which is a dual sim, but not a real dual sim, the second sim slot is for the SD card, which i know is how it is over here, but for some stupid reason it tracks within the phone as a second sim slot.
I am on rogers in Toronto, and the phone works fine with one small glitch. I don't get LTE. I only get 4g. While in europe i was getting 4g+ (whatever that is), but for some reason LTE doens't work.
I am going to check with the samsung service centre to see if I can change the csc to canada, and maybe that will solve the problem, but it's in a mall and with the holidays I am not going to attempt going there until after the new year.