I have used the 270 in Idaho for many years and have found that the trajectory of the mid-weights to be quite astounding! Depending on the humidity and wind velocity (in combination with the early morning/late evening barometer readings), the high data paradigm readings came in a little low for my preference. In those cases, I used the 30-06, but in some cases I have not been able to get the 30-06 off my horse in time to shoot. I still believe however, that the 270 and it's 1456 fps. at the normal 92 degree quadrangle is your best bet! Good luck in Idaho - and be careful not to get lost - I got lost in Idaho one year and almost didn't make it out. If they find you frozen to death in that nasty country, it won't matter much whether you were carrying a 270 or 30-06.