The simple answer to the OP is that the higher the fare you pay the higher up the list you will be for that particular flight. That is about all you can interpret looking at fare class of your ticket. There are lots of other factors in play as to whether you will get the CPU or not. Your status, your route. How many people lower than you decide to use miles or certs to upgrade. All those can push you down the list. And I still haven't quite figured out the new thing about 1K and GS on instant up fares and lower elites on instant up fares.