I am assuming you mean choosing betwen swapping barrels or replacing this rifle with an off the shelf model. It depends, IMO, in the type of performance you're after. A factory "off the shelf" rifle is unlikely to perform like a custom rifle and to make the modifications necessary to get that performance will cost as much as a custom rifle.
If your current rifle is a factory model then I wouldn't bother with a new barrel. I'd just take the action and build one on that foundation. Therefore, IMO, "is it worth it" depends on the performance you want.
Oh; OK 'jt" .. I see where you're going. The only real advantage I see in swapping out to .308 is the wider range of bullets you might find available for that one. But that advantage alone would not, IMO, make the swap cost effective.