If you cancel the extended warranty do you have any warranty left?
I also had the extended warranty (3 years in total) as he gave it to me for free when I bought it new. Never needed it. You'll find the vast majority of riders never have any problems, but then there are those who do have problems of course. Just a couple days ago there was the thread about the bearing going bad, the warranty thankfully covered it (several thousand dollars
To be honest I would be less concerned if it had more miles on it. If it's a factory fault like a broken bearing, it most likely won't suddenly break after 15000km, but may very well break in the first 8000 km. Of course there are exceptions but I would say that holds true a lot of times. The first 10k km are the most crucial and likely where if a component is defect/inferior quality it should fail.
Also ask him what work/mods you can do to the bike without voiding the warranty. I think technically you are not allowed to do any engine related mods, so that would rule out a programmer or the likes (what about the exhaust?). From what I read in the past here it seems like the US dealers are a bit more lenient regarding this stuff. Mine insisted I come in to do oil changes as well to be on the safe side the warranty would cover me for sure.
I think the moral of the story is to go with your gut feeling