French bike plates are generally plastic not metal and although the numbers/letters are smaller the police are still as hot on enforcing/fining for "bending" the rules and they're having a real crack down at the moment (plates, exhausts, indicators, etc. etc.)
Me on the other hand with a tiny plate on my S4 and one that's nicely hidden on my Z get away without any probs or fines as both are UK registered and over here on "holiday" ...is 8 years still classified as a holiday
There's still no MOTs on bikes and won't be until 2012 at the earliest