Used for shooting deer at 800-1000 yards I would give the 6.5x284 more than the slight advantage being discussed over the 25-06AI. Comparing the the 115 and 140 Bergers, the 6.5x284 with 140 has 30-40% advantage in energy at 800-1000yards and more importantly much better penetration due to the 30% better sectional density of the bullet. The deer I have shot at those ranges have had complete pass throughs with substantial tissue damage on broadside shots. The higher muzzle velocity of the 25-06AI takes it in the neck due to the inferior BC of .479 with the 115gr. compared to 140gr at .612. At the short/ mid ranges, the practical differences between the two begin to diminish.