We are concerned about proc’ing a stat that can be readily capped especially on an item that provides a rather large passive armor pen bonus already. It could end up just never being attractive enough. Right now we are strongly considering just having it proc base-stat (strength, agility, etc.), haste, or crit depending on spec. We’ll be sure to let you know if we make this change.
Apparently they weren't kidding. Reports are that the new procs are agi, strength...and haste. Which is much better than arpen since chances are you're either soft-capped or close to being hard-capped.
Whereas haste just makes you more awesome. And there's no real danger of hitting the hard cap any time soon.
So if you were at all in doubt about whether or not you should get this trinket: you should get this trinket. It's going to be significantly better than anything else save what perhaps Arthas drops, all three stats are going to be a huge boost to DPS by themselves, and all three are very valued by druids. Point of fact, this might make a good argument for DBW going to ferals first; with this, even assuming best in slot trinkets DBW should be about a 200 DPS upgrade over the next best thing. Currently the stat value itself is worth around 300 DPS by itself; the proc is another 250. This will increase the DPS value of the proc by about 33%, making it close to a 650 DPS trinket - and that's the normal mode.
I know that rogues don't care about it nearly as much (they don't care about arpen as much); neither do enhancement shamen. I would imagine that it's going to be arms warriors and DKs, basically.
And you can bat your eyelashes and say how lovely it would be if you'd get it. :)
Also, this makes it the premiere threat trinket for bears. 600 haste is a lot of extra mauls.