I think they are both good cartridges and are almost identical in performance,that said the WSM got off the blocks first and is chambered in more firearms,loaded by more companies,available in more different bullet designs,and ammo is available at the local wally world.The 300WSM and 270WSM will probably go the long run while the 7mmSAUM will probably be the Remington offering to last at this point.Don' t sweat an inch of barrel length either way.

woods