Not the same situation, visiting is not the same as importing.  I
would expect under visiting you would 'pay' the Honda dealer to repair
and then be reimbursed by Honda US.

With respect to the original question, there is likely to be minor
differences between US and Canadian models and you need to submit the
vehicles for inspect and certification at an approved centre.  When I
imported a Volkswagen Golf into Canada (Halifax) I took it to a
Volkswagen dealer to find out what was required then took it to the
approved centre (Chrysler Dealer) for inspection and certification. In
my case there was nothing required, off hand I can't remember the fee
but it was not significant.

[snip]

No debate there, Tony.  I realize they can tell which market the car was
made for/delivered to.

Do you know for a fact that Honda Canada will send you packing back to
the States?  For that matter, what will they do if I take my American
delivered Honda up to Montreal on a business trip and the transmission
fails?  Tell me to go back to an American dealer?  Doubt it.

Hi,
They know the origin of car by serial number. Then you go back down to
U.S. for warranty service. Very inconvenient.

Anything to back this up?  It would seem to me that you're saying that
if I buy a Honda in upstate NY and then move to Ontario when there's,
say, 15,000 miles on the car after 16 months, I'm screwed if something
goes wrong if I try to have it remedied by Honda in Canada.

Doesn't sound correct.

No, it won't--not any more than the Honda Canada warranty will be
honored by American Honda.

Here y'go. Straight from the horse's mouth:
http://www.riv.ca/english/html/how_to_import.html

RIV is the Canadian government agency that handles vehicle importations
into Canada.

Generally speaking, the American Honda factory warranty will be honored by
Honda Canada Inc.

With the Canadian dollar being stronger then the US dollar right now, and
the Civic SI costing about $23K US in the States and 33K Canadian in Canada
I'm thinking it might be worth the effort to buy one from the states.
Anyone have any experience or suggestions on doing this?

My understanding is I won't have to pay duty as the SI is made in North
America.  I will just have to pay GST at the border and get some sort of
Insepection done to the vehicle?  Sounds like a small amount of work to do
to save $10 000