Logically speaking, based upon the way they process CPUs, yes a higher fare class will put you ahead of lower fare classes dependent upon your status.

Reality though, CPUs are so hard to come by IMO with low costs F fares and TODs.

As others mention, the day you are flying, route, inventory (how many F seats), etc will all come into play.

To me, I would never try to purchase a higher fare class in hopes of obtaining a CPU. If I was going to do that, I would just purchase F outright - heck, majority of time that means it would be cheaper than many Y fares.

It's like playing the GPU lottery of paying more money to hope your upgrade clears, except here, it would be for a CPU. I don't play those games.

UA just needs to get better about selling F and helping instruments clear, as well as recognizing their elites better. In current state, TODs are king and what UA feels is the best strategy. Until TODs are gone, our CPU hopes will lack, regardless of fare class.