I have three 10-box teams up and running ATM. Last week they all downed VoA10 and Marrowgar

Their class make-ups are as follows:
Team Mag: 2 prot pallies, 1 holy priest, 1 resto shaman, 2 locks, 2 ele shammies, 1 hunter, 1 boomkin
Team Pant: 2 prot pallies, 1 holy priest, 1 resto shaman, 1 lock, 2 ele shammies, 1 hunter, 1 boomkin, 1 mage
Team Merc: 1 prot pally, 1holy priest, 1 resto shaman, 2 locks, 2 ele shammies, 1 hunter, 1 boomkin, 1 prot warrior

As you can see, I've moved toons around a bit to be hitting close to the same composition with each.

As Cata approaches, my goals are:
1) to continue to push into more bosses in ICC (at least through Rotface)
2) complete some professions for the 5-6 toons above that don't have professions maxxed
3) level up another team of 5 from 70 to 80 to give myself options for team tweaks

In regards to 3), I'm going to level up a team of 1 prot pally, 2 holy priests, and 2 mages. You can guess who the prot pally may replace , the priests might be replacements for a couple of the resto shammies (at least I want the option of doing so), and the mages may replace the boomkins or possibly hunters depending on how Cata comes out.

I like my healing setup now too - for healing-intense fights like Marrowgar I convert one ele shammy to resto, then just have one resto shammy healing each tank and cover raid heals with the priest. However, healing is sooo important that I want options if healing rain turns out to suck or something.

As for DPS, my mage and warlocks are consistently my top DPS. An equally geared mage may even edge the locks, and arcane mage rotations are stupid simple, hence the mages as options.

Hope that helps you as you think things through.

BTW, misdirect from the hunters is the way I start all my fights, then I can just go balls to the wall from the beginning.