A thread asking which trinket was best for DPS encouraged me to plug in every trinket I could think of into my TPS spreadsheet. I found some surprising results.
Comparison:
Shard of Contempt: 50 TPS
Romulo's Poison Vial: 35 (If the proc is affected by threat multipliers)
Tsunami Talisman: 32
Icon of Unyielding Courage: 30
Ashtongue Talisman of Valor: 27
Madness of the Betrayer: 27
Dragonspine Trophey: 27
Gnomeragan Auto-Blocker: 22
Berserker's Call: 20
Hourglass of the Whatever: 20
Interesting. I would note that this doesn't take into account "snap" threat, though. Part of the reason the Auto-Blocker is so useful is that it's a huge up-front threat contribution, allowing you to open with 3-4k threat and reduce the chance that DPS pulls on early critical hits or whatever. So while it may contribute less threat over a long fight, it's the "opener" that really makes the item useful to me.
This is true on Trash too. A great way to multi-tank I've found is to use the auto-blocker to shield slam an off target at the start of a fight. One good shield slam is usually enough to hold aggro on him until I'm actually ready to start building threat. It's like a permanent taunt (provided nobody is DPSing that target).
Good findings, and like kerchunk said, the benefit of the Autoblocker isn't Threat over the course of a fight, it's the help it provides during that most crucial moment of a fight: 0 aggro.
I tend to run with the poison vial and the shard most of the time, unless I need more stamina for certain fights.
So here's a question - is the shard of contempt always at the top of the list, even after you push dodges off the chart? If you can reach 23 expertise before you equip the shard, does its tps drop on your spreadsheet?
The Shard is modeled assuming you are above dodge cap and at least 44 expertise rating lower then the parry cap. If you aren't, then the value of it goes up rather drastically.
I wear like 7.75% expertise in my survivability set, so I imagine most people most people will be above 5.6% in their threat set.