Do you reload? If not, it will probably be easier to find ammo for the .300 WSM. I doubt the .325 WSM will still be around 5-10 years from now. 8mm just never appealed to American hunters.
Did you consider standard calibers like the .30-06 or .270? These are all anyone really needs. I understand "needs vs wants" :lol:, but if you don't reload, and want a .325, you might as well start learning now.