I feel the most important thing is to have a limit.
There is no doubt that some aircraft can handle crosswinds well in excess of the max demonstrated limit. But, as long as you stick below that limit, you
know you're in territory which the aircraft can handle. As soon as you go above that limit, you're entering the realms of a test pilot.
If it's been demonstrated to you (e.g. by an instructor experienced on that type) that your aircraft can handle xxx kts, even though that's 5 kts higher than the POH limit, and if that higher crosswind is also within your capability, you might consider that to be safe. Then, that becomes your new limit, which you don't exceed. This is assuming you've checked that your insurance will still cover you, of course.
The danger, I think, is in using the general statement that "aircraft can safely exceed their maximum demonstrated cross-wind limit" to justify flying in cross-winds which you haven't experienced before. (Unless you are a test pilot, of course.)
Personally, the own 'plane I've flown in crosswinds which exceed the POH limit is the Super Cub. The first time I did this was with an instructor. We did several circuits, and every landing was well within my capabilities and that of the aircraft. I set my personal limit in the Super Cub to 17kts based on that. (I forget what the POH limit is - I think it's 12kts, but can someone confirm?)
In the Europa, on the other hand, I don't have the confidence to fly even close to the demonstrated cross-wind limit yet. I will gradually work myself up to it as the opportunities arise, setting my personal limit slightly higher than cross-winds which I've experienced in the past and dealt with successfully, and I know that these limits will be within the capabilities of the aircraft. I have spoken to lots of Europa pilots, including test pilots, and most (but not all) of them say that the max demonstrated crosswind really is the limit in that particular aircraft. I have no intention of trying to prove them wrong!
FFF
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