Long term I feel that diesel or JetA1 is the way to go. Avgas can be extremely difficult to get in some remote locations these days, not to mention that you will pay through the nose for it if you can get it. Avgas these days in PNG is basically not available anywhere, even Moresby these days and the large operators who are using piston engined aircraft are having to import their own Avgas into country as the fuel suppliers aren't generally stocking it now.