Actually, in the event that the seats are dumped to F during the EUA-able window, miles have priority only in the event that you notice this conversion has happened, and you call CO immediately to process your upgrade. Your U/G generally will NOT clear. I am speaking from experience on over 25 segments attempted to upgrade w/ miles. On many of these, I was assured that my WL segment will be processed when an F seat becomes available. But only after losing out on two separate trans-con reservations, I noticed the trend.

So, my advice is to keep checking for F seats during the EUA process, and when one becomes available, call CO immediately.