Based on what you've stated as the intended use I see no reason why your 270win wouldn't work just fine. If your just yearning for something new, different and a little more powerful, then I'd suggest the 7STW over the 300RUM.
Lots of shooters here shoot and love the 300RUM. It is probably one of the best cartridges for tossing heavy bullets at high speeds across looong ranges.
With that said, the 7STW will is more than adequate for the job while consuming less powder, being less expensive to shoot and generating less recoil. It is also a very accurate cartridge when fired in a quality rifle.
I've been shooting a 7STW for years so maybe I'm a bit biased but it seems better suited for your intended use. /ubbthreads/images/graemlins/laugh.gif
Besides, once you get the buying itch again you can get another rifle in one of the RUM cartridges. /ubbthreads/images/graemlins/grin.gif
VH