I just had this conversation with my dad for like 3 days over a long weekend. I told him it's a fantastic round that he shouldn't buy, which confused the heck out of him.
Here's my argument against 30-06:
* The existence of .308Winchester
1) Find surplus ammo for practice
2) You mag capacity is lower
3) The action is longer
3.1) The gun is now heavier
3.2) The bolt is usually wobblier
3.3) The scope has less flexibility to move front and back
4) The hunting ammo is usually a bit more expensive
5) .308 can kill anything 30-06 can
In the end I actually told him to go buy a Tikka T3 30-06 simply because it doesn't matter which cartridge is better, it matters what you're comfortable with. He owned a Sako 30-06 in the 1970's, and the Tikka has the same action length regardless of calibre, so 308 would have been long action regardless. Modern bullet construction really makes it so any cartridge that can push a premium projectile of 130g faster than 2500FPS is a big game killer, so you may as well pick whatever is shortest, most available, cheapest, and comfortable to shoot. There's even 7mm-08 which isn't too shabby.
What's funny is that the guy at the gun store started going off about .270 vs 30-06, it's such an easy argument to make, but it further confused my dad:
* Beyond 150y .270 is better than 30-06
* Below 150y .270 is going to kill anything it hits
* Therefore, .270 is better than 30-06
* Buy .308
I really wish that clerk wouldn't have brought up the .270 because I had to then agree that it was better than 30-06
I just think it's funny how he started off wanting a 30-06, I told him .308 is better, and now I'm trying to convince him to get a 30-06. He has more experience with the 30-06 than the .308 but he's so convinced that .308 is better now.
I have this feeling I'm going to be buying him a T3 in 30-06 just to stop him from calling me every week to go over this. It's hard enough trying to explain why rifles don't come with irons sights, and why the stocks are plastic now.