I'm GS and I have itinerary for 3 passengers booked on UA flight in couple of weeks as Standard Coach award (HN class) using my miles. Pax are GS as well.

I have wait listed this for Saver Business Award (IN class), but could also use a GPUs to upgrade (R class). Upgrade is not available to confirm yet, but chances look decent (over dozen open seats and good revenue inventory still left).

I was told by GS agent that both IN and R come from same inventory, and thus there would be no advantage in likelihood of clearing if I changed from Saver Business Award to GPU. Can anyone here verify if this is accurate?

Looking to maximize the upgrade chance, less concerned about optimizing mileage use or instrument value.