Considering that the 912UL sips cheap Mogas at a very low rate, and all the other sundry costs related to aircraft ownership/building, would this alleged saving be of any significance?
UK Mogas is ,locally ~£1.25 a litre...£5.68 per Imperial gallon (4.546 L)
Assume a "normal,carburetted" burn of 3 GPH, and assume the saving
is 25% with injection, that would be 3.4 Lph....(£4.26 )
a hundred hours a year would save £425, so well over 10 years to recoup the extra cost, even ignoring the loss of interest or cost of the extra 5K initial purchase.
Personally, I'm a big fan of injection....beautiful clean burn must be good for the engine as well as the wallet. It's normally robust and maintenance free, doesn't wear unpredictably like carbs...and , usually, doesn't falloff or introduce mystery induction leaks due to perished mountings.
Having said that, The rotax application is IMO, grossly overpriced,
though I have just seen a price for overhauling a pair of Rotax carbs and it made my eyes water...I really did lose my way, mending cars and motorcycles!