The Rem. SAUM's are in the books. Have a 300saum in the 673 Guide Gun and am very fond of it. The wsm's put a hurtin on the saum. I will have to disagree with GB on the wsm's not living long. IMHO the 270 and 300 WSM will be around for ever. 7mm wsm may be on the the bubble. The 300 and 338 RUM I feel will make it. with the 7mmrum and 7mm stw, only one or neither will last.
Having a 300saum, 270wsm ,7mmrum, and 300 rum, at least I'm two fer four, at least for now. I also think the 270wsm will last over the 300wsm for the simply reason that there is a larger margin between the 270 win and the 270wsm, but the 300wsm and 300wm are very close balisticlly.
again JMHO, DM