WRT purchasing a Class A in the US.  We were told if you trade in your Class A in the US for a new Class A, when returning to Ontario you pay the HST on the full amount of the new unit.  If you trade in Ontario, you pay the HST on the difference between the cost of the new unit and the trade.  Can anyone confirm this.  Also a dealer in Florida informed us that a new rule has been instituted in the past year and you have to pay 6% duty at the border.  If all this is true, I fail to see where it is worth buying in the US and going through the steps to get it inspected etc. for licencing in Canada.
A couple of years ago there was a US made unit we were interested in but it was not certified for Canada due to the way the propane lines were run.  I think you have to be very careful and do your homework before deciding to buy in US.