Yesterday I looked at T5 for cats, where I learned that the 2/5 Tier 4 bonus is so amazingly great that Tier 5 isn't really an upgrade. But Tier 5 isn't the only source of cat gear. How about Badge of Justice gear? Which slots should we buy items for while preserving the 2/5 T4 bonus? Turns out the answer is easy: chest, hands, and legs.
Here's the kitty points for T4 gear vs. the best available Badge of Justice gear. Relative to my stats (3300 AP, 41% crit).
T4 BoJ Diff
Head 255 254 -1 Mask of the Deceiver (50)
Shoulders 182 n/a
Chest 236 319 83 Tunic of the Dark Hour (100)
Hands 143 213 70 Handwraps of the Aggressor (75)
Legs 189 324 135 Trousers of the Scryer's Retainer (100)
So if you're choosing between T4 and BoJ gear and want to keep 2 pieces of T4, you should keep the T4 helm and shoulders. Until I'd sat down and looked at the loot tables I hadn't realized there were no BoJ shoulders. And the old BoJ hat is not so good.
I picked up the chest yesterday. It looks ugly, but the stats are nice. It's also good for a bear threat set; on Void Reaver yesterday I held aggro for 90% of the fight with three prot warriors also smacking on him.