I don't think you'll notice much difference in damage between a 338Win and 270/30-06/7Mag on deer.

Yes, there is much more energy, but not any more velocity. And velocity is what creates widespread destruction and devistating wound channels.

You'll really notice a difference on much larger animals, like Kodiak or Moose because they are big enough to absorb all that extra energy. Remember, once the bullet passes though, which all of those will on a deer, all the remaining energy doesn't matter b/c it's not on target anymore.

If you are looking for the most dramatic effect possible, try the 200 Gr Win BST at 2950 fps.