They lab test and rate their oils as in JASO and ISO. All the good oils are labeled 2T for high speed air cooled engines and then rated using these standards. Look at a bottle of Stihl Premium and you'll see a EGD rating. It's good stuff.
There are slightly better oils out there like MOTUL 710. Any oil good enough for air cooled 2 stroke racing motors will carry a rating of JASO FC/ISO-L-EGD. Valvoline and Sunoco make oils over here that are fully rated this good. They are not horribly expensive and work well.
I don't know if Amsoils products are rated? W/o lab results you have no idea what you are buying. If they are rated, then comparison shop the ratings and buy what you like.
All of my saws are old enough to not have warranty for a decade or so, so I'm on my own. I run MOTUL 710 at 40:1 for the Swedish iron and Valvoline EGD 2T for the rest - also at 40:1. Been working for me for a while now (like 40 years or so, using the better stuff when it comes on the market) and my powerheads last a long time. Usually something breaks, or the plastic gets brittle long, long before the motor quits.
I tried 100:1 once in a leaf blower (Red Max) and ate the motor (running rated full synthetic). Rebuilt it and have been running 40:1 ever since and that machine is at least 15 years old and gets run for hours at least once a week year round. Comp is still good and it makes power. I'll never do 100:1 again - ever