The .25-06 AI isn't much different than the 257 weatherby. Both need a 26" barrel realize their potential. My 25-06 has a 24" barrel, and I certainly wouldn't want it any shorter.

I had a Remington 700 Mountain Rifle chambered in .257 Roberts. It shot like a dream, but it was a short action. To get the accuracy, I usually had to seat the bullets out far enough that they would no longer fit in the box magazine. The rifle favored the lighter bullet weights. It shot the 85 - 100 grainers very well, but the accuracy of the 115-120 bullets often left something to be desired. My best loads used IMR 4350 and Nosler 85 and 100 grain Balistic Tips. The 100 grain Hornady spire points also shot really well.

I sold the rifle before moving to Alaska. In hindsight, that probably wasn't a great move. I will have a heck of time finding another one.

If you enjoy handloading the 257 Roberts is a fine caliber. If you don't go with the 25-06. I own both and reach for the 257 more than any other in my arsenal. I can reach an honest 2926 fps with Hornady 117 gr. BTSP out of my Remington 700 with a 22" barrel. With the same bullet I reach 3088 fps with the 25-06. It also has a 22" barrel.

Like stated above if you handload give the Roberts a try. If not stick to the 25-06. One thing to note. My Roberts was a special run of the Remington 700 Stainless Classic. It has a long action. The OAL I use to reach good accuracy is too long for a short actions box magazine. So, I guess if you need a long action for the Roberts why not just buy a 25-06?