My personal and limited experience suggests this whole demonstrated limit business is somewhat inconsistent.
The US aircraft do seem to be consertative in this respect. I've had the oportunity to land both the AA5 and Arrow outside of the demonstrated limit in about 20kts of crosswind component and it was clearly within the limits of said aeroplanes. Indeed, the French types seem to have quite high limits, the Robins, Socatas and Wassmers with demonstrated limits of 25kts, which I imagine would be more challenging than exceeding the demonstrated limit in the Arrow.
On a point of possible interest, the Cub has a demonstrated limit of 10kts and frankly I find it challenging landing it with a component of only 8kts. The Super Cub a demonstrated limit of 12kts and yet again about 8kts was challenging enough for me.