Answer from VN boardThe armor type just has to do with weight.
Since the more cc the character has the more it affects initiative and AC (@ 50% and 70%).
There for if two pieces of armor have the same AC, say +9, but one is light and one is heavy the main difference is the weight and the effect on CC. The light my only weigh 18lsb while the heavy could be upwards of 32lbs. Now for you fighter and Valkyrie types this isn't such a big deal b/c they have large CC so the heavy is a better VALUE.
But for someone like the gadgeteer who has to carry around a lot of heavy ammo and gadgets it might be worth the extra gold for the light armor. Then you can carry more impaling stones, quarrels, etc. on their personal invetories and not have to always go into the pary inv. I also like to give my ranged char some close combat weapons like swords and shields and these can weigh a lot.
Hope that helps.