B Fare MQM and upgrade
 

Traveling Sunday main cabin on a B fare class, good for 150% MQM. If I am upgraded at the gate to F, which is likely, does the 150% MQM drop back to 100%?
If so, I would opt to decline the upgrade and instead collect the extra MQM.

ETA *Oops, thought I was still in the AA forum!*

You always earn based on the purchased fare class.

+1 on always earning based on the purchased fare class. Sometimes the DL systems have issues with this if you're using upgrade instruments on partner metal; but with run-of-the-mill DL marketed & operated flights it's generally not a problem.

However, most (all?) FC fares earn at least 150% MQM anyway so if there was an error, it can actually sometimes be in your favor. :)