At the risk of getting back on topic I'll also say that if the 300 PRC would have been around when I bought my 338Lapua I probably would have leaned towards the 300 PRC. Hornady has made some incredible design improvements with their "PRC" series calibers to the point where the rifle manufacturers would have to try to make the guns not shoot well.To the original topic though between 300 WM and 338 LM I'd go 300WM. Personally though I would probably choose 300 PRC. Especially if you're planning to hand load. 300 PRC is the next caliber I'm planning to add to my collection. While it isn't exactly cheap to shoot, it's pretty reasonable considering what you're getting. I don't think the recoil on them is all that bad either. And it's hard to argue with the ballistics.
Whatever you end up going with, let us know what you settled on. Then give us an update later on about how you like it.