I remember hearing somewhere that each armor set will have heavy and light variants.

I only recall hearing that a file for a heavy/light variant of Starhlim was found.

Stahlrim was used in Bloodmoon to make Medium Armor, so it could be the material can be used for LIght or Heavy armor. If they do it right, it should take more Stahlrim to make Heavy than it does light.

However, for other materials, they are either Light or Heavy and the armor that results is the same. In otherwords, your not making Bonemold or Chitin armor Heavy.