Has anyone tested yet if upgrading your seat to ELR works to trigger the credit?

I'd have to imagine it would, as that's the whole point of the credit, and those upgrades are typically never more than $84 (when you go to the seat selection screen as a Cardholder or A-List holder).

Keep hearing horror stories about Basic fares getting reassigned at check-in, despite having chosen seats due to CC or A-List perks, and am considering just burning some of my Amex credits on guaranteed ELR seats.