Armor Retention Question

So I'm curious as what ya'll have found as the best way to keep yourself equipped while leveling classes that do not have the same armor type. As a PUG/MNK I know at some point I'm going to have to level MAR for a specific move. In my armory I have PUG armor from my journey. I sit there and I tell myself I should keep that for lancer and archer but then I feel like a hoarder. So what do I do with all this armor, just sell it/materia it and buy from vendors when I level them up? The other half of this is progressive armor for hand jobs. I feel like I should keep all of these for maximizing success by level when leveling those classes. Any advice is greatly appreciated.

I haven't been stressing about it all that much. Up to level 15 at least, gear is pretty cheap, and doesn't make an enormous difference (for battle classes, anyway), outside of the weapon. Anything I level much past that, eh, it'll work itself out one way or another. I'm neither meticulous about clearing my inventory nor squirreling every little item away.