Originally Posted by RAPC

Correct points, just the YQ seemingly doesn't get added (or charged) when the calculation is made by the agent. It has certainly been mentioned a few times in this forum craigthemif where people have been surprised at the reduced cash element for a late upgrade on the phone. I have benefitted from it personally a couple of times when UC inventory opened up 72 hours before departure and we've upgraded.

Spot on about airport upgrades. They are very much reliant on what is available and whether VS want to gain additional revenue from those seats. Plus you get the last pick of seating, so groups may well end up spread across a cabin, even if you can pay to upgrade.