Been lurking here a while - the site and forums and site are a fantastic information source - thank you.
So, running Heroic Sarth +1D and I was very excited to win the Dragonstorm Breastplate. However, once I equipped it, my +Dodge dropped by 0.5% and my block dropped by a whopping 2.5%. Parry increased by 1% and I gained 400HP. I am currently wearing the T7 Heroes' chest. Current content consists of Naxx 10 & 25, Sarth +2D, with planned Ulduar 10 incursions soon. Here's my Armory:
I'd personally use the Dragonstorm for progression, T7 for farm content (for the 2 piece bonus, and that is the only reason). Dragonstorm beats it handily all around otherwise. Once you get another T7 piece the T7 chest is one of those trash only type deals.