I've used a 7mm on Elk and it is fine. However, as I started venturing into long range on a more regular basis, I decided I would step up in caliber for any of my elk hunting that would be more than 400yds. I don't know your particular situation, how heavy of a rifle you want/need etc. So I'll just tell you what I have and what I use them for.
I have a 338 Allen Mag for any extreme range hunting I need to do. For me this is anything more than 700yds or so. (I like being over gunned) This rifle weighs 18lbs and is a beast to carry around at altitude.
I have a 13lb 338 Edge for a 'lighter' long range elk rifle. I feel comfortable out to 1000yds with it on an elk.
The third 'elk' rifle I have is the previously mentioned 7mm Rem Mag. It weighs 8lbs and is a walk around 'light' rifle. With the 160gr Accubond, I'd be very comfortable out to 600yds or so. The rifle is so light that it is difficult for me to shoot it in field situations farther than that.
If I didn't have an elk rifle at all, I'd probably go with a 300 RUM and call it good.
AJ