2 sides of tailoring? There are three. :D Shadowcloth, Spellcloth and Primal Mooncloth. If you are 100% sure you will be staying shadow at 70, then the obvious choice is to become a Shadowcloth specialist. This means that every four days you can make 2 shadowcloth with one set of materials, rather than only one. You can still make the two other kinds of cloth, but you only make 1 cloth every four days. The three pieces of frozen shadoweave gear are the best pieces a shadowpriest can get until tier 5, perhaps even tier 6. More than worth it.