There are so many opinions on this subject. I understand where you are coming from, I felt the same way when i started out.

Your engines are top drawer products. Follow the manufacturers respective recommendations on this issue, especially if still in warranty.

My .02:

For many US produced engines, it seems to be that break in on mineral air cooled 2 stroke oil is preferred, then switch to a quality full synthetic, after "X" gallons.

For many European engines, the recommendation is best quality synthetic from the start.

I find it hard to believe that the metallurgy is so different there needs to be a differing procedure.

In motorcycling circles, some guys are known as "oil weenies" and obsess about the "best oil" for their bikes. I like to ride, I buy a good quality brand name oil I can afford, and be done with it. $50 a gallon for Supa-Doopa Synth 2-stroke SlikkerOil from Lichtenstein? It might be great stuff, but no thanks.

I bet my engines last as long as theirs. I believe the same will apply for my R/C engines too.

I use good synthetics made for racing 2 stroke air cooled bikes I find in my motorcycle shop. I am happy and so is my bike, and my 'plane motor. So far, the 'plane motor runs beautifully and internally the motor is very clean. Shell Racing M, Mobil Racing 2T, Castrol TTS, Fuchs Silkolene air cooled 2 stroke, there are many good brands. A good bike shop proprietor will carry a range of different manufacturers products, and can advise. I am sure Amsoil is also a fine product.

I am wary of 100:1 ratio's or anywhere near that. Maybe I am paranoid, but flying in Summer in 95 F heat with this low a ratio scares me.

So no need to stress. Buy a good product, run at recommended ratio and rest happy. Oils are not tomatoes. They don't go off if stored tightly capped in the original container .

Personal opinion only.