Wow.
While I'd expect this kind of debate regarding the .243, which is on the small end of "legal big game caliber" in most western states, I'd never have expected us to have graduated to making the case that the .25-06 is insufficient on deer as well.
What's next? The .270? After that, the .30-06? After all, they're not THAT much bigger than the .25-06 and are all based on the same case....
I lived in Archuleta County in my youth. It's where I started big-game hunting. My neighbors there owned Pagosa Hardware for a time. Back then, if you used a "magnum", you were using a .300 Win, Wby, or H&H. Mr. Alexander kept a few Weatherby rifles in the rack for "tourists", but most of what he sold and stocked ammo for amounted to .243, .30-30, .270, .30-06, and yes, .25-06. Alley Mercantile never sold rifles that I recall, but stocked ammo in basically the same calibers.
Why the history lesson? It wasn't until the "magnum-craze" of the late 80's into the 90's that suddenly the tried-and-true deer and elk calibers now became "too small". Now you go the ammo shelf and have to negotiate a myriad of .300s and 7mms. The deer must've mutated and are now larger than the record muley that was taken back in the early 70s.
Having taken antelope, all species of deer, as well as elk with the "tiny" .243, I take issue with the prior statement that "caliber plays a role". It takes a role, yes - but a far overrated one in comparison to shot placement. I saw plenty of deer hanging in camps this fall with holes blasted in them in nearly every body region BUT the boiler room. Yeah, they were all dead, but it often makes me wonder if that was the first deer the hunter shot at, and if not, how many wounded ones were left to crawl off and die? I heard an awful lot of multiple shots this year, where I should have heard just one.
A poor hit with a big cartridge is an irresponsible substitute for a good hit with a small cartridge. I'm no fan of the .25-06 (it's too in-between what I currently own), but I see no logical reason why one shouldn't use it on muleys, PROVIDED they handle it well.