not sayin the 25-06 doesn't work, of course it does, and it works well. The 260 just works a bit better, all things being equal
My 23" brl 260 does 2975-3000 f/s with a 120gr TTSX, try doing that in a 25-06. You'd need a specialized twist which isnt common in factory guns. It'll also do 3250 f/s with 100 grainers, right there with 25-06. My neighbour's MkV Ultralight 25-06 does 3280 with the 100tsx.
260 just plain works better, simple to see
Going by and utilizing info from the Sierra manual, and as luck would have it their test rifle virtually duplicates what I'm using. As pictured in post #10, a Savage 112BVSS with a 26" barrel, 1 - 10" twist.
Doing 2975 - 3000 with a 120gr Sierra 120gr HPBT, no problem. About a week after I shot the target in post # 10 and hs4570 signed it, he brought his chrony to the range for our next session. I have the data he listed for me and I'll see if I can dig it out. There were a few loads he chronied for me and as I recall, using the Nosler 120gr spitzer solid base, Sierra 120gr HPBT, the velocity range was from slightly under 3100 to a little over. With the 110gr Nosler Accubond, 3200 and just under. With the 117gr Sierra and the loads I was trying, right around 3175. I have some Barnes 115gr flat base triple shock but I haven't tried them yet.

I'm a little curious as to what you've stated, about
needing a specialized twist. The 25-06 Remington - 1 in 10" in the following;
- Remington 700, 40-XB.
- Ruger # 1 and 77.
- Browning.
- Sako.
- Winchester 70.
- Savage 110, 112.
- Thompson/Center Rifle.
In most of the 25 cals, are 1 - 10" and some 1 - 9 1/2" and one I see, the 256 Winchester in a Marlin 62 is listed at 1 - 14".
Now in the 260 or 264 range of diameter calibers, there are quite a few twist variations, all the way from 1 - 8" to 1 - 11". I'm guessing that with some of the tighter twists, will have a tendency to reduce velocities although improve the handling of heavier bullets.
On my recent trip to the Terrace area, I picked up a Chronograph at Misty River Tackle & Hunting. I'll have to get it into use when the weather improves and the rain stops.