I don’t think there’s an animal alive that could tell the difference between a 30/06, 7mm, or 300WM within 300 yards. Yes, the WM will shoot a little bigger bullet a little faster than the 30-06, and a 7mm will shoot a little faster than the 30-06, but they are all great cartridges that will take anything in North American and PG in African with proper bullets and shot placement.
I lost my dad a little over a month ago, and will be getting his 7mm and 300wby. He killed 13 elk in 12 years with his 7mm, and I’m hoping to add another big bull to its talley this year.