Having nearly gone through the entire process, I would argue that it's only barely worth it (depending, of course, on how much you think your time is worth). The cost-savings is only a side-benefit. The real reason i need to import is the variety of used 370Zs in Canada is almost entirely useless. So many more options in the US, and I've found the exact car and options that I really wanted.
The latest scare I had was the odometer. The RIV requires that your odometer must display the distance-driven in KMs. However, on the 370Z, the odometer is digital.
I just confirmed with someone at Nissan North America (who phoned a dealer in Stanton Island) that the odometer can be set to display in metric units. So crisis averted!
Hopefully I'll have it on the good side of the border by next week Monday
Wish me luck.