RE: Can the 30-06 *really* do everything a 308 can?
The .308 is not significantly more accurate than the 30-06. This myth was started because M1 garands rechambered in the 1950s were much more accurate than m1s chambered in 30-06. The reasoning for this disparity was that the m1 was not originally designed for the 30-06 cartridge and could not use the cartridge to its full potential or even use the best propellants in the cartridge for that matter. A top end highly tuned long range bolt action rifle chambered in 30-06 can actually outperform an equivalent rifle in .308 in long range shooting as the bullet from the 30-06 starts out 100 fps faster. Long range competition shooters usually skip the 30-06 altogether and go right to the 300 wm to get additional velocity over the .308.
To answer the original question, the 30-06 can do everything the .308 and then some. I personally have rifles in both chamberings and don't particulary favor one cartidge over the other for what I use them for.