My thoughts as well.
I am asking because I have an opportunity to fly an Air Tractor 401 with the Orenda this coming week during a seminar.
Our 5 and 600 gallon planes are equipped with the PT6's and although I do not see any chance of replacing a PT6 for the Orenda I thought what the heck fly it and see how a V8 engine performs.
In our industry the Orenda's theory is not to replace the PT6 powered airplanes with the engine but to upgrade from the P&W radials (1340 primarily) at a fraction of the cost (advertised). So far I do not see the savings with the 1500 hr TBO and still having the cost of avgas, plus the fact that with only 600hp the airplane will be restricted to a smaller 400 gallon payload. Maybe over the old, tired radials but never with the turbines.
Maybe I'll fly it just for kicks and giggles.