Why DK+4Rets instead of 4Rets+Enh Shaman?

[Heavyd]

Wouldn't the Shaman bring all the same buffs (and then some) to the team? I just wonder if there's something i'm missing.

[Ualaa]

The DK will make a much better PvE tank then an enhancement shammy.
Although with dual-specs, you could go Resto Shammy and Prot Pally for PvE.

Death Grip is a nice tool in pvp.
As is instant cast Path of Frost, while already mounted.. especially in AB.

I know some are looking into different teams.
Still with a DK on the team, but an Enhance Shammy in the place of one of the Rets.
Instead of in the place of the DK.
Purge is pretty huge, and some of the totems are quite nice too.