I doubt it's fuel related, if detonation is a problem surely there would be damage evidence on pistons. Doesn't take long to start to melt a piston with detonation.
Dmech could be on to something with resonance.
One thing I am sure of , Jabiru don't know what is causing them to break. I had to just shake my head when they put out a SB changing the nuts for nuts with more thread???? It wasn't the nuts that were the problem. Just fitted new bolts to 2200 and they came with bigger 12 point nuts that required using a 1/2" crows foot(instead of 7/16"). Bolt diameter remained the same, yes that should fix it,really?Tom