Wing down Vs crab? It's down to what you've been tought and what you're used to. I once checked out in a school in the States prior to renting an aircraft. The CFI insisted I did the wing down method as that is what his school did and 'it was superior'. After cocking up a couple he declared that 'I had obviously never flown taildraggers' (actually I had about 1500 hours on them) so I demo'd a perfect crab method on the other runway with 25 knots of cross wind. He conceded.
Also, what id a limit? If you look at a lot of aircraft's POH (esp American ones) the crosswind is a 'max demonstrated cross wind', in otherwords it's the maximum the manufacturer has tested to. It's up to the operator what he does with that limit - whether he want's to treat it as a limit or not. I flew a very large jet with two companies. One treated it as an absolute limit, one left it to the pilot's discretion.