Here's a great example of what cheap premium cabin fares have done to upgrade availability: SFO-ORD on the 772 this Friday . . . J and F have been booked full all week, flight status shows 8 upgrades to J, 0 upgrades to F.
When they start using the HD 772 config on this route, we will see flights going out with J filled 100% revenue, zero upgrades.
Not a complaint, just an observation.