Buckfever,
Sorry for the late reply but we have had computer problems.
I have to agree with GB and others that in the real world, you really won't notice much of a difference between a 270/130gr and a .30-06/150gr. Your Tikka is a fine rifle - no questions asked, and the .30-06 cartridge is a great cartrdige. Even though mule deer are not big as elk, they are certainly larger than whitetails (or at least as big as the northern monsters). As such, I would like to have at least a 150 grain bullet on mule deer at shots over 200 yards - even on well placed shots. If you are talking about 350 yards, then I really advocate the 150 grainers.
I know that recoil is an issue, but I find the 7mm Rem Mag to be an awesome longer range cartridge. The 7mag has a bit more recoil than the .30-06, but I find it to hit with more authority.
Keep in mind that I have nothing against the .270 winchester. Heck, I own a couple of them. If you really want a .270, AND shoot 130 grainers, then I would alternatively suggest you shooting super premium bullets like the barnes-X or new TSX.
As for the gun itself, honestly, if you are going to put it through some abuse, then forget about the Cooper. While it's a great rifle, I would hate to see it scuffed a lot for you- which it will. As such, I would go back and recommend what you have, the Tikka T3. Given that it has a one size fits all action (all long), then the .270 will be just fine.
Other than that, I also recommend the Remington, but not necessarily the new, new ones. See if you can find a BDL SS. I own several of them and I love them almost as much as my Tikkas.
Zachary