I have read quite a bit on this issue and as best I can determine, they began using the steel washers sometime during the 2008 model year, so some 2008's have them and some have the old ceramic, but everything made after 2008 should have the new ones.
However, and this sounds weird to me, I have also read that they only went to the new washers on the supercharged engines in the jet skis and they are still using the ceramic washers in the boat engines to this day. I don't know if that's accurate or not, but they're all the same engines and clearly they know they have a problem with the ceramic washers, so why on earth would they only change them on the jet ski engines and not on the boat engines? It doesn't make any sense, but that doesn't mean they're not doing it. I would call BRP directly, ask for someone in engineering and get clarification on this. That way you will know for sure whether the boats were included in the switch or whether they are in fact only addressing the issue on the jet skis. If they say they are also using the new washers on the boats, get it in writing -- ask them to send you an email confirming it so you have some documentation. Hope that helps.