You noted both cartridges are very accurate. For this reason, not taking bullet choice into consideration, I would take the 7RM for Elk. Personally, I would like a little extra punch if you will. I'll let others chime in on Core Lokt as I've never shot them. Use the other cartridge as your backup. Realistically, either choice will work.
TTSX is fine but needs velocity to open up well. Barnes says TTSX will open up down to 1800 fps, LRX 1600 fps, but when you look at pictures of barnes bullets with minimal impact velocities the bullets do open but marginally. Probably not much more than the diameter of the bullet itself. For this reason, I like to keep my impact velocity > 2200 fps for Barnes bullets. I simply look at my ballistic chart, find 2200 fps, that's my max shooting distance. For one cartridges my max is 478 yards. For my other cartridge my max is 601 yards. I don't shoot over 400 yards. 2200 fps rule that I like to use doesn't change my max shooting distance (hunting elevation). However, if I were at sea level that may change.