Certain pieces are quite good, but primarily they're focused on DPS over tanking. That's not universally true, though... the Shields in particular can be exceptionally good. The S3 Shield is the best shield you can see until the Kaz'Rogal shield, for example, simply because of the Armor and Stamina, and the other shields are worth looking into depending upon what other shields you can acquire.
For DPS, look at each piece individually. As a general rule S2 is superior to T4 and S3 is superior to T5 (or equivalent pieces, although the Honor pieces tend to be decently worse than equivalents depending upon which one you look at), but that isn't universally true. On the flip-side, though, the S1 BP is a very nice pickup since the T4 BP is relatively difficult to acquire (Magtheridon) and even then is a rather minor upgrade, so... there is no hard and fast rule, just guesswork and then looking at each piece side by side and figuring out which once you want to get.