There is no disputing that going to a longer barrel will increase velocity, range, etc. My recommendation is soley based on the fact that you can reload and tune your gun for less than re-barreling which would cost you $1000 at a minimum with a good quality match grade barrel such as RockCreek, Lilja, Hart, Gillard, etc.
Even if you did re-barrel you'd still require handloads to obtain the best out of your rifle.
If you are considering re-barreling, I would also recommend having the rest of the smithing done at the same time, such as Trueing action, work done on bolt, trigger if it has not been done already, bed gun and free float barrel. If the smith has the gun apart and is already machining things up with the new barrel then that would be the time to do the rest.
Good luck