My experience, in equal barrel lengths, is the 300 WSM is 150 - 200 fps faster than the 30-06, but RL17 will make the difference closer to 250 fps faster.
For ranges beyond 400 yards the additional velocity of the 300 WSM is nice to have but not necessary either. The real plusses of the 300 WSM over the 30-06 is the plethora of ammo available for it, all of which is loaded to the gills. The other plus is the 300 WSM is chambered in the excellent Kimber Montana.
A sub 7.5lb "all-up" rifle that launches 180's at 3K is a lot of rifle in a handy, light package.
