The sticker thing is a pile of bollocks and there are huge numbers out there that don't have them for aircraft that they have flown for years.
There are a load out there that say you have grandfather rights that as long as you have some time in your log book from pre JAR you are able to fly them.
I got someone to sign off stickers for VP prop,pressurisation,retractable and EFIS. Just in case but then again I have never flown a SEP with any of the above.
I don't think it matters just now but come EASA things might change. I can just see some french inspector wanting to see your differences training and the sticker is at home in your first log book.