The main advantage with the .30-06 is more distance. But, like limbkiller said, if you're inside 400 yds, the .308 is just fine. Besides, you will perform better with your own rifle.
Sounds like an awesome hunt - good luck!
Christopher A. S. "Boots" Combest
Member: TSRA, NRA, GOA, North American Hunting Club and Ducks Unlimited
"If you get thrown from a horse, you have to get up and get back on, unless you landed on a cactus; then you have to roll around and scream in pain."