Been wanting to try the 2.5-20 as well I have the 4-32 and rarely find myself going above 20x. Mounting is the main reason I haven’t picked one up as well.
Elk are just tough in general. I watch a bull swallow 3 rounds from a 30 Nosler with 215’s he was dead on his feet after the first shot they are just tough.
If you reload and have a custom rifle with the correct freebore the 7 prc isn’t that impressive minus being non belted. Factory ammo that shoots with heavy for caliber bullets is the benefit imo.