Day of departure upgrades are a plus IF you are already ticketed on a YBM fare due to either last minute travel or no Saturday night stay. The fares that are eligible for upgrade with either a PMU or lots of miles are already much higher than the lowest coach fare, in most instances. As someone else has stated, a $350-400 surcharge per BE leg could be justified, but not a surcharge of $1000 per leg plus PMU or mileage.

I will either buy I fares, or the lowest coach fare and hope for an operational upgrade. As I said, the benefit of day of departure Z upgrades comes when you were forced to buy a YBM fare in the first place. It will allow a high fare revenue passenger to get those BE seats instead of clearing non-revs off the standby list.