What do France, Germany and Canada use?
I've flown in locally registered aircraft in all three countries - and they all used X-XX.
Actually, my experience here the last 3-4 years is that in France pretty much everyone uses only the last two letters, so that F-GAVK would become VK...this applies to ATC too, not just at small French only fields. Not saying thay officially everyone is supposed to use the F-XX format, but then we are talking about relaxed and practical flying France here
Regards, SD..