RE: rate of twist in 25-06
Both cartridges are damned good. Fact is, they are so close that until you get bigger than caribou there isnt a dimes worth of difference. Granted the 25-06 will shoot flatter. The offset is the 270 will do for elk. Barrel twist on the 25-06 should be right around 1:10, which is the same as a 270's twist.
I have a 25-06 and am amazed at how well it shoots. It is one of those cartridges that usually shoots better than it really should. My favorite groundhog load for that rifle included a 87 grain bullet doin just shy of 3400 fps. Very deadly on little critters. For deer, I prefered 120s. They worked real well on several deer.