I don't own either, but from what I have read the 7mm WSM should offer a slight advantage in volume since the neck is shorter. However, the shorter neck is also a disadvantage as you have stated. So its the short neck with greater volume or the long neck with reloading advantages. I don't think you can go wrong with either.
Last edited by Shortmagman; 03-25-2008 at 09:46 PM.