The WSM's have a cultish following in the long range precision game. You see more of the 7 WSM'S the 300 WSM is a good hunting round. As for the 7 WSM the 7 SAUM is more efficient with less powder (meaning a slight bit less recoil). Brass is hard to come by though. If you really wanted to push the envelope build a 300 or 7 WSM on a long action so you can long throat them.

That is how I built my 7 SAUM. You can get impressive results this way.