Internal vs. external boom outhaul

I will be ordering a new boom very shortly. I must now decide if it is worth while to salvage the parts off of my old boom or to order it complete. Most of the parts are in fine shape. I'm wondering two things. First, what are the advantages of the internal 6:1 outhaul over the external 6:1 outhaul. Second, am I in for any surprises, or difficulties in trying to remove all of my fitting, and installing them on the new boom tube.
I must also consider the fact that my boom is still in usable condition in light air, there is a small hairline crack near the boom vang, and maybe it would be a good idea to keep it intact for possible future use.
Any thoughts would be greatly appreciated