Personally, I rolled 3xShammies to go along with a L70 Shammy, my first ever WoW character. I've played the class extensively, so I know what I'm doing in terms of Shamanizing.

I played the three of them together from L1-12, mostly to figure out my basic macro structure and get a feel for movement issues. But using my other L70s is so much faster and convenient, and I don't have to worry about gearing them up or what not.

I figure I'll keep hammering out SM until I hit 40, by which time I'll have full set of Scarlet Mail armor for all of them, all the totems I will need (for the most part) as well as Chain Lightning and (almost) Chain Heal. At that point I will probably switch to outdoor questing.

In all likelihood, I will use my L70 Shaman with the three newbies once they hit L40 and run instances that are more L40 appropriate. This will give me a chance to further refine my macro/totem strategies on all four guys, even if their levels are still disparate.

It's also quite tempting to start letting my L70 Pally tank for them, and give them (well, me) some practice healing/DPSing in instances using a very durable meat shield. For Outlands, I plan to quest/instance with the 4 shammies and my pally anyhow, and avoid the open world PvP scene for as long as possible.

For now, I'm having fun with an "optimize SM Cath run" mini-game on my mage. The shaman team getting some levels out of the deal is a nice benefit as well.