I always used my 7 mags for elk, but I would not feel under-gunned with the Creed. There have been LOTS of elk and other critters killed with it. If I was going to hunt elk with one, I would lean toward a little more durable bullet. I really like the 147 ELDM, but I would not personally use it on elk-although some have. I would go with a Partition, Accubomb, or one of the coppers. I think that I would be looking at the 127 LRX, pushed as fast as your rifle will tolerate. Another one that is tough and mostly overlooked, is the 140 Interlock. That bullet will also kill just fine.
I have killed a lot of deer and some antelope with the Creed and .260, both. 6.5 bullets just plain work well. My personal favorites, are the 129 Interlock and the 147 ELDM, but I would probably not use either one for elk. I am currently experimenting with some Speer Gold Dot, 140 bonded bullets that would probably work real well on elk, too.
Lots of good choices out there. Just pick one that will hold together and shoot accurately in your rifle.