Insurance.
I alternate between MP Bolshaw and HR Jennings - I normally insure one aircraft with each company but tell them that I am having the other quote, too.
Bolshaw's coverage for the aerobatic aeroplane is pretty good and worked out £400 cheaper than Jennings. The quotes for my vintage aeroplane are within a few quid of each other so I tend to swap them around every couple of years.
Traffords did settle a claim against travel insurance with all fixed wing flying risks, after a mate of mine had an horrendous accident in RSA. Initially they stated that they would only pay 70% of costs because the accident happened during an aeros trg sortie and aerobatics was not covered. Ultimately they agreed to pay 100%.
Hope that this helps.
Stik