Originally Posted by anteater

I can't speak from experience, but I would guess that it should work. AS is reticketing an in-app paid upgrade into a full fledged FC fare basis ticket. So, when it comes to exercise a SDC your ticket should be treated as a FC ticket. Whether that is what AS intends or how it will work in practice.. you can let us know. ʕ•ᴥ•ʔ

I could also see AS eventually putting a clause in the SDC T&Cs that state equivocally what's allowed.