I wouldn't sell one for the other. If you've hunted much with the .338, you won't notice much difference. They both buck and hit hard. The biggest difference I notice is the rifles - my .338's are all scoped long guns and the .350's are open-sight carbines. For Alaska or Africa, keep your .338, a standard international caliber. The carbine is easier to carry, but .350 is hard to get ammo, so I wouldn't take it anywhere on a plane where you could get separated from your ammo. On coyotes, the carbine swings easy and gives you a bit more range than a shotgun. It doesn't red mist them like squirrels, but it comes close. I put an Eotech on a newer 673 .350 for this coming season. Wound channels are graphic and wounding shots with other rifles like a .223 or .243 are deadly with the .350. It throws a pretty good flame and it's loud.
If you're thinking about buying one of the new 673's, I'd do it ((I really like mine)) but I'd figure out another way to pay for it.