I can't tell any difference in recoil between my 30-06 and .300 WSM. They weigh about the same and are in similar rifles (.300 WSM Featherweight and .30-06 Extreme Weather). In fact I notice more difference in recoil between a .270 and .30-06. Also, ballistics are not much different (a couple hundred feet per second at the VERY MOST and I think that may be stretching it in that most loads in my WSM are about 100 fps faster than a good '06).
Haven't hunted elk with a .300 WSM, but have with a .30-06 and .300 Win Mag. I am not the elk expert, but say they will both work. Take the rifle that you shoot best with.
