Your name has always dropped off the gate list if you boarded.

My understanding with the old system was that it was much harder to upgrade someone who had already boarded.

My understanding with the new system is similar.

If you want to sit in J, don't make their lives hard.

I've now personally witnessed a "battlefield upgrade", which I hadn't on AC when I started this thread. But I have now, and my opinion hasn't changed.

Do not board if your upgrade hasn't cleared.