You have my sympathy on the small engine problems with your yard gear. So far, I've had no problems with my 2 year to 6 month old engines and hope that holds up.
I will say though that it is BS on the engine manufacturer's part that they have apparently not done the small specification changes (mainly materials used for elastomers, fuel lines and such). Whoever is working on your engines should be up on the exact materials needed and just switch out his replacement parts inventory, unless he is just trying to assure a greater amount of repeat business. 10 or 15 years ago when ethanol in gasoline was phasing in, I can understand the tangled up mess of fuel system materials and incompatibilities, no excuse now though.
If you have a drag strip or airport close by, it would be lots cheaper to get some racing grade fuel or aviation gas than that outrageous $22/gallon stuff. Robbery!
Agreed. Ethanol has been around for enough years that the small engine makers have no excuse for not adapting.