The Sierra manual shows loads for both using a Savage with 26 inch barrels.
There are 6 max loads for the 06 at 3100 fps with 120 grain bullets.
There are 3 max loads for the AI at 3200 fps with the 120's.
I have a 25-06 and never considered the AI. The comments in the manual are attached:
Dating back to only a decade or so after the introduction of the parent 30-06, the 25-06 is one of our oldest wildcats. Despite its potential, it wasn't until after the Second World War that the cartridge really came into its own. The greatest hindrance to the 25-06 prior to that point was the lack of slow-burning powders needed to deliver peak performance. Even with their arrival on the handloading scene, Remington didn't standardize it as a SAAMI cartridge until 1969. This lack of appropriate powders explains P.O. Ackley's lack of enthusiasm for his version of the 25-06 Improved. Since the parent cartridge already had a bit more capacity than the available powders could effectively use, the resulting additional seven or eight percent was wasted. Because of this, he recommended the 257 Roberts Improved as a better all-around cartridge. In the past few years, handloaders have been presented with an ever expanding range of slow-burning powders. Some are actually slow enough to make use of the 25-06's added capacity, turning it into a truly viable cartridge. With these, the 25-06 Improved has started to realize its true potential. There are few 25 caliber wildcats that can exceed its performance, and in fact, few that can even match it. Among the major factory cartridges, the 257 Weatherby stands alone as the one offering that can surpass its performance. As with any extreme cartridge, there is a downside to attaining such speeds. The 25-06 Improved does not lend itself well to being downloaded. Barrel life is also an issue that should be considered carefully before chambering an Improved. Use as a round for big game certainly won't be a problem, nor will occasional shots in long-range varminting. In the prairie dog fields, however, it would be easy to burn a barrel out in relatively few sessions. Used with discretion, the 25-06 Improved is a good performer for long-range, medium-size game hunting.