jpbar,
I think you got that one right. They are essentially the same round. The WSM has the advantage (if you wan to call it that) of a shorter bolt throw. It also had the disadvantage of more expensive factory ammo. But if you reload, that's not a issue. If you do a lot of traveling and hunting, you may just want to stick with the 300 win. mag. Ammo for the 300 win mag is pretty widely available. The shorter fat stuff may be harder to come by if your in....win-a-puck nowhere, 15555.
MHO
Dave