First off, grats, I wish my guild was in that content.
The only thing I'd recommend is the Shard of Contempt, and if you can spare the stam (hard choice, I know but for fights were threat is a MUST) you could go with the Shard and the Blocker over the Commendation.
Really u should have no threat probems with that gear at all. ur hit is great and ur expertise is great and with the GAB u have a good amount of BV. if u can tank gorefiend without having anyone catch u on threat ur doing perfectly fine. doing 1000-1200 tps on average is good u don't need mcuh more for any fight in BT.