I should note that one-way vs round-trip shouldn’t make a difference as far as upgrade likelihood is concerned.

Also, what is the ORD-YUL segment? I fly that route a lot and while there are some UX170s/175s, most of the flights are either UX 145s or Air Canada 175s, neither of which will give you upgrades via CPU (though Air Canada may op-up if they are oversold in back and undersold up front, but your difference in UA status won’t matter because all Air Canada knows is that you are *G).