Given the performance of a turbine Glasair I suspect that tips the 'balance a bit.
From what I recall a RR250 is around $250k, the hot end inspection at 1750hrs is about $80k. An IO540 $65k - fuel at 60 lt/ht - say $150 in the Uk. So $260k in fuel for 1750 hrs, plus the initial 55 makes $325k. The turbine still works out rather more expensive - but the performance is very impressive. I've seen this aricraft fly and if I could I would!
Given the ability to climb near vertically the costs do seem to be worth it!
Better hope the tax on JetA1 does not increase - it would deprive us of some spectacular machines