I have a few of each and think that the 25 Souper is a better fit COAL wise in short actions and the 25-06 is an easier option in long actions.
If the 51mm case length of the 260 made it an inferior option in short actions, I can't see how the 55mm 25-284 or 57mm 257 Roberts cases won't run into the same sort of COAL issues in short actions with longer/heavier for caliber bullets.
