All subclasses share a lot of the same basic moves across the board. I had read somewhere that BW intentionally set classes up this way so that healers and tanks could level as efficiently as their dps counterparts.
I've been in flashpoints and heroic groups with Commandos who are spec'd dps but did the instance as heals. I've
"tanked" (term used loosely at low levels) lower level flashpoints on my Shadow even though I am spec'd as dps. I'm used to the WoW dynamic where you don't want a healer spec'd spriest as your dps and you don't want a spriest trying to do heals...likewise for most classes in that game...so this throws me a little.
Is there a certain level where classes start to pull away from each other? For instance, is there a certain level when dps spec'd Commandos can't heal through flashpoints or heroics?