Same bullet weights can be fired to same speeds in 30-06 and roughly 100-150 fps faster than 308. The difference in .03" greater bullet diameter is roughly the same as your fingernail. In other words it doesn't make a hole enough bigger to matter.
But that .03" greater bullet diameter means much worse BC's in the same bullet weight.
The 30-06 beats it at all ranges, 308 is slightly behind at the muzzle, but passes it at around 100-130 yards.
I'm loading 178 gr ELD-X's in my 308 at 2650 fps. At 300 yards I'm only 32 fps slower, but with 1869 ft lbs.energy. I don't know how the drop at 300 compares to 338 fed. But I do know that if zeroed at 100 I'm hitting perfect POA with the 200, 300, and 400 yard dots on my scope. I'm not concerned about flat trajectory with a BDC scope. And I'm doing it with less recoil than 338 Fed.
I can't think of a single reason to choose one over a 308, let alone a 30-06.
If you'd prefer a short action as I would, it's a better option than the -06.
As for the 308 vs 338Fed, not too much in it. But there aren't too many flies on a .338, 200g SST at 2700fps. They hit considerably harder than the .308, 165g version at about the same velocity. (I've shot a good few pigs with both combos FWIW.)
