Wow 19.5% in Ontario? That's nuts. We only pay 6.1% import duty for non-NA built vehicles and then 12% HST here in BC. Unless you're combining the two numbers which isn't quite accurate either cause you pay HST on the value of the car plus the 6.1% import duty. I still did pretty good with my import and came out quite a bit ahead. Definitely was a bit of a concern getting the car sight unseen but the dealer was reputable and the Carfax looked good. You can get an independent inspector for about $150USD to give you a report. Some of them even take the car for a test drive to ensure nothing is out of ordinary.
iDrive is not a deal breaker and I thought I'd be okay with it before I got my car but now I'm glad I have it. The car just feels more complete. But it doesn't affect the actual driving experience I suppose. The M button again is a nice to have. I use it firm up my shocks, set the steering effort to sport, change throttle mapping, and shift speed whenever I know there is a nice set of curves to tackle. Setting all of those on the fly would be hard since you'd have to take your eyes off the road. As for the start up defaults, yes it does load a set of defaults but those are completely separate from the M preset. Also the start up defaults don't include certain things like steering weight, just the three main buttons next to the shifter. It does remember your last used shift speed but only for D mode. S mode always defaults to 3 bars. These startup defaults can be loaded by using the control stalks I believe.
To reiterate I don't think the OP has found a bad car. It's not the best deal he could find in the US but I think it's still quite a bit cheaper than the comparable used Canadian car. The plus as other's have mentioned is that he gets to test drive it and check it out in person.