My boomkins have not done heroics, or even an instance yet.
They're all one-spec, Boomkin!

So far, with all the toys they get, they've been the most fun team.
As far as questing and slaying of world mobs goes.

Not exactly sure how well this translates into instance power.
Having had a 1x Paladin and 4x Shaman group...
I had a real shock going with a Bear tank in a mixed group with macros.
A click sequence could not hold threat -- and I've one boxed a bear tank through a lot of BC raid content.
Was kind of a shock. But having split the attacks into three keys has helped the mixed team.

My 5x Boomkin will be a PvP focused team.
More interested in BG's then Arena (lacking in burst, will see what Catacylsm brings).
But the same 210 badges which buy Tier 9, also buy the PvP equivalent.
Which will be one step behind current 25-man raid/arena season gear.
Or a lot better then you can get with honor alone.

So they'll likely venture into heroics, to see what they can manage.
Have the spec and glyphs for 1x Feral and 1x Tree dual-specs ready.