5 Shammy or 4 Shammy and Pally

I saw a few nice videos where a 5 man shammy team has successfully cleared the TBC heroic dungeons. I was planning on a pally and 4 Shammy for the same thing, but wonder if a pure play of 5 shammy might be a better choice.

For those with experience in both 5 Shammy boxing and 4 Shammy/1 Pally boxing, what would you say are the key differentiators between the setups?

Is any one group better for a combo of PvP and PvE than another or is 5v5 PVP still going to require one char to sit-out so you have a healer?

we are doing 4 shamans 1pally, should be 70 in a week or so, and we will keep yah updated.

Once you get into heroics the pally tank is probably going to be a bit better. You might lose some speed in killing things, but you have a designated meatshield for your pseudo squishy shamans.