I've got 2 in the safe right now. Will a 7 Mag kill elk? Sure.
I'm not here to be a Doom & Gloom on the 7RM, but both of mine have been safe queens for quite some time now. Why?
I found I have done just as well with my 7mm/08. Although there is a new 338Fed in my near future.
If a 7RM is what you want, and you can shoot it well, then go for it. A 150-160 AB/PT will serve you extremely well, so don't blame the bullet if elkie doesn't flop !