2nd unit Pally, Mage, 3x Shammy

So I am thinking of doing a second 5-some. I have a 70 Pally and Mage that are pretty well geared on Doomhammer. I am thinking of adding some Shammys to complete the 5-some. I am wondering if you guys think this would be a good combination or if 1 Pally and 4 Shammys would be better. Any advice is always welcome.

Also do you think that Shammy is going to continue to be the MB powerhouse class that it currently is in WotLK??

Thanks

My current set up is a prot Pally tank, arc Mage dps, 2 ele Shaman and 1 resto shaman. I just hit level 50 this weekend and it's pretty sick how well they do in the instances. It's a great team. Earth shield on a prot Pally is really great.