I don't have experience with either, but, if I was going to pick one, I'd go with the RUM, since it's available with factory loads to different power levels. i.e. .30-06/.300 Win Mag/ and full power .300 RUM...
For comparison purposes, I think the chart at Chuck Hawk's site makes for a good starting point. On the various rifles I've shot, felt recoil seems to about match the differences he shows on the chart...
http://www.chuckhawks.com/recoil_table.htm