Chadster - I don't think the .25-06 is "better" at long range, but it's a viable choice and with the very light recoil, it's a peach to shoot. I've taken five mulies in the past five years with the .25-06, and for me it's pretty much a perfect mule deer cartridge. The last three have been with the 115 gr Berger launched at about 3200 fps. Great combo!
For me, the Berger VLD and slow burning Retumbo powder made the .25-06 a good choice for longish range shooting/hunting. Mine is a simple 700 CDL, all factory, a sporter rifle. But it has been very effective on coyotes & mule deer.
Nothing wrong with the bigger cartridges for long range, and they'll deliver a heavier bullet. My favorite for longer ranges is the 7mm, particularly with 160 - 175 grain bullets launched at 2900 - 3100 fps... A well-loaded 7mm Rem mag will do that easily. I also do a fair bit of longish range shooting with the good old .308 Win, which on paper doesn't necessarily look real good for the job, but it just seems very easy to get great accuracy out of it out at 600 yards.
Regards, Guy