Not sure that anyone has boxed Cataclysm stuff.
That would require having several accounts in the beta.

Looking at your proposed team, it should work well.
Pallies are an excellent tank, as a boxer.
You have three ranged DPS, which is generally easier than melee.
And a dedicated healer on the team, meaning you can do whatever DPS you want and not need them to heal.

I personally don't like a Hunter on a ranged team, because they switch to melee when things get in close.
And if I drive the tank, any kind of a flying pet is in my face.
My top choice as a replacement would be another Elemental Shaman, although a Warlock would work too... or if you have a Priest, dual spec both the Priest and Shammy, so you have Shadow/Disc and Elem/Resto... ultimate flexibility in encounters and the option for extra healing if you need it.
Then again, if you've already played the composition and liked the Hunter for level 80 stuff, it will likely be very similar for level 85 stuff.

Boomkin has the new Eclipse mechanic to worry about, or ignore as you choose..

Looking at crowd control effects or options.
Hunter has Frost Traps, Mage has Polymorph, Boomkin has Root/Cyclone, Shaman has Hex.
Pally has Divine Intervention, Boomkin has battle rez, Shammy has self rez.

Also, your team has some measure of flexibility as is.
You can tank with the Pally or a Feral Bear.
You can heal with the Pally, Druid or Shaman.