Thanks for the replies and it does seem to be a very complex issue. However is there any route forward based around the safety record of individual types? The reason I ask is that I flew a Tecnam Golf in New Zealand. They don't try and force it below 450kgs but openly operate at 544kgs which allows two crew, full fuel and baggage in an uncertified airframe (although it is built on the same line as the certified airframes). It is nominated as an "advanced microlight" and this pragmatic approach has led to 33 being sold in the NZ alone. To my knowledge the safety record is 100% so it can be done. There is a new version called the Tecnam 2002-JF which is certified but 50% more expensive because of certification. It seems like Catch 22 to me.