the reason I say the 25-06 is based on federal premium ammo compare of the calibers.

check it out yourself..
http://www.federalpremium.com/ballistics/Ammo_Search.aspx?act=choose&firearm=1&s1=1


.243----100gr Nosler Partition for all 3
25-06---115gr
.270----150gr

.243..........speed in feet per second @ 200yds.....2386
25-06................................................ ............2518
.270.............................................. ................2464

I know you lose some energy with the 25-06 compaired to the .270 but I prefer the extra speed and less bullet drop long range compaired to the .270