OE (not OEM, our bad) is not what you are showing in your link, that is their Signature Series.
OE is synthetic 0W-20 but designed to be changed according to the factory recommended service interval.
XL has a longer service interval, 10,000 miles or six months, whichever comes first.
Signature Series has an annual or 25,000 mile service interval, though they recommend following manufacturer guidelines for replacing the oil filter unless you use their extended life oil filter which is good for 1 year/15,000 miles.
I changed my oil at 1200 miles to OE with a Subaru filter. I will change it early fall to Signature series, then change my oil filter at 6 months, and do another oil change next year in the fall.
I will probably keep using Subaru filters (I have 4 in my garage waiting), they are cheaper than the Amsoil extended life one and changing them once a year midway between oil changes should take me 5 minutes.
Right now I have about 4,400 miles, so that is 3200 miles with Amsoil OE and no oil loss. I didn't see any reason to use Signature Series for my early oil change as I knew I would change it once more this year anyway.
I drive less than 12,000 miles a year. I am comfortable with the extended life oil and using Amsoil in my car and I plan on driving this car for a long time. YMMV.