So apparently the official forum search function blows today. Therefore you'll have to take my word on the following statement:
It is generally considered that the Wildfury Greatstaff is better than the Earthwarden for tanking.
When my guild went on their first trip into Serpentshrine Cavern, I wasn't able to go, but another Feral Druid did. While she was there, the Greatstaff dropped for her. She linked it and all were happy.
I checked it out (as I couldn't remember the stats on it at the time), and I came to the realization that I didn't really want it. For months and months I've been reading from other Druid tanks that this is the best tanking stick they've found and many claim to have vendored their Earthwarden within moments of leaving the Caverns.
People that speak in favor of the Earthwarden are frequently belittled and marginalized.
The thing I can't understand is: why?
I understand it brings significant dodge, that it has almost 500 more health than the Earthwarden, and that it's significantly more Feral AP. These are all good things for a tank.
When I considered what I'd lose, though, I couldn't bring myself to use it as my tanking stick.
First and foremost is the Defense rating. While a great many Druids are engaging in PvP for the Resilience gear with high armor and mitigation stats, not all do. I am doing some arenas for gear (as my Armory likely shows), but this really only reinforces my point. There just isn't enough other gear in the game to abandon a stick like the Earthwarden without very careful consideration. For a PvE-only Druid, there is no other viable option for this slot if you are using the Defense.
Before 2.3, there was Feral Combat Skill, but since that's no longer in place, we'll deal with its replacement, Expertise.
My GM is a tank and as such we occasionally lament tanking issues. One thing that both of us agreed was extremely high on our wishlist for tanking gear was +Hit. Now, with recent additions to the game via Heroic gear and Feral PvP-re-itemization, there's a lot more of that available than there has been in the past. That said, the Expertise on the Earthwarden is extremely appealing in spite of it.
Expertise provides a reduction of 0.25% per point to your target's chance to dodge or parry attacks. Earthwarden has an Expertise rating of 24, which becomes an Expertise of 6. -1.25% chance for all my targets to dodge or parry when I tank.
Best of all, it's immune to Defense skill. That's HUGE.
I'm not sure I can express how vital this is especially if you deal with undisciplined dps or run Heroics where healing aggro (due to the major heals required) can be fatal to your lifeline, your healer.
The Wildfury Greatstaff gives me none of that. There are times, no matter how rare they appear to various individuals, when that missed attack can mean the difference between keeping aggro and losing it to someone that can't survive the attention.
So in spite of the dodge and health buff, the rest of my gear isn't yet at the point where swapping out the Earthwarden for the Greatstaff makes any sense. Until I do some math with a gear list, I'm not sure that day will ever come. I'm incredibly durable as it is, and while I never scoff at mitigation stats, I've come to realize that there are some items that may - at first - look outdated, but that retain value due to factors often overlooked.
I tend to think back to when people were complaining in the early days of the Burning Crusade that the Kara epics were sidegrades rather than upgrades for the lion's share of gear. Back then I learned to realize some rares were better than epics and that's a philosophy I'm trying to hold to. Just because the iLevel is higher doesn't mean the item is necessarily statted appropriately.
Maybe I'll use the Greatstaff for a resist fight but I can't see any other place for it right now. For me, the Earthwarden has a continuing role as my primary tanking stick.