I was a Druid, Natgul, on Hakkar EU Server, and i was MT in all TBC, with Huge Armor, Max HP, a 55-60% dodge in raid.
Now i have a DK, and i try to tank Heroic and OT raid using Frost and Unholy spec, deep and talented as Tank.
From my point of view, and looking for the next pacth, there are some point for turn back my Druid as Tank or multiutility:
1) Damage Incoming: An Unholy/Frost tank, have much miss-rate defenseve stat (def + lichborn every 3 mins), but during the encounter, when the IBF or BS/UA are in CD, the incoming damage is very high; Druid have a costant -12% damage from PotP, magical and physical, and a copy of IBF (not improved by def), named Barskin (usable when stunned of feared).
2) The Lichborn antifear is equal at the Druid Berzerk;
3) Blizz says they look for a new avoidance/mitigation utility for Druid, based on "?????", but great for matching the dodge (now, a friend of mine, have a similar level of my DK equip on his Druid, and in tank form have 42K hp in raid, 38% dodge, i reach only 36k buffed).
4) The incoming nerf for BS and IBF, make the DK an extreme CD-based tank, and when cd are gone, bye bye dk...
5) Blood is a terrible tank, have healing counter-mitigation ability, but the damage incoming is incredible, and not really mitigate...(thinking an AoE pull, 15k damage per second).
I hope the new frost presence include a flat mitigation for physical damage, or we must pray the cd is ok when the blow coming in our face...
DK have a great AoE DPS, great in 1 vs 1, but for tanking, at this moment, can't MT in raid.