I guess my problem with the rotax conversion is that the 916is is $50,000. My A&P friend is helping me rebuild an IO-320 which we are going to be able to rebuild for under $30,000. It would have been under $23,000 except for having to replace the crankshaft that ended up having a crack in the oil hole. Even if i decide to put FlyEFII system 32 on it instead of overhauling the mags and carb it will top out around $33,000. You can buy an superior IO-320 for around $36-37K. The 916IS will burn around 5gph and the IO-320 around 7. call it $4.25 for 91 octane fuel which the IO-320 will burn and you are saving about $8.50 per hour. Even at the more expensive end of the IO-320 that is over 1600 hours to break even and more like 2000 for me and the overhaul cost will be higher. I guess it is really hard to swing that extra cost, and i didn't even factor in modification of the airframe costs, when I am trying to keep my costs down. If they could figure out how to get the 916is under $40000 I think it would a lot more palatable