Just like the 300WSM is a short action 300 Win mag. Very little differance in performance (velocity) but there are definite advantages as listed in my first post. You can only propell a certain weight bullet so fast w/o blowing everything up. You can however propell it to the relatively same velocity more efficently, with less weight, and the real possibility of better accuracy.
Just like a 67 camaro will do a 1/4 mile in XX seconds and so will a 2003 camaro but the new one does it more efficently and with less emmissions. What is the extra cost in these cartriges besides the slight cost of the ammo? The guns cost the same, the scopes cost the same, the rings. A box or .270 Federal HE TBBC costs me $35 a box and considering the cost of an elk hunt the cost of a slightly more expensive box of ammo is nothing. Also considering the cost of Weatherby guns and ammo that argument doesn't hold much water with me.
The only thing in life that is constant is change.