Apparently Canada Post now scans all First Class and Priority Mail packages. That being said, I've still had some challenges with things not arriving in Canada, even with scanned tracking. The USPS claims there's no way to file a lost mail claim, or issue insurance claim on ANY package weighing under 4lbs- even if it's Priority Mail. I'm not sure what happens if you buy insurance outside of the Priority Mail $$. I spent a long time with the 800# folks and spoke with several people, but there was no traction.
Might be worth looking into Fed Ex. Costly, but it gets there in just a few days and fully certified the whole.