I can link umpteen logs where I'm managing to push very significant DPS on some of the nastier pulls these dungeons have to offer (EG 6K DPS on Ala Mhigo double gorilla packs + dogs).
Not all healers can stomach throwing out holys on a pull like that, but to say that it doesn't give us the opportunity is a fallacy.
I'd also add that if you're not saving time with large pulls, your group simply isn't aoeing hard enough. The run linked above took 15 minutes total, I contributed over 20% of the total damage done despite some brutal pulls and very skilled DPS. On a more typical pug run, I can contribute 30%+ and again, have the logs to back that up.
In short, big pulls doesn't necessarily require you to sacrifice healer DPS. It's still very dooable and mightily effective. Until the other thread throws a decent SCH log at me, I'm firmly of the stance that WHM is the undisputed champ in these situations though and that's something that does need to be kept in mind.
It's also worth reminding that this sort of damage isn't something you should expect from your healer. Rather it's something your healer can choose to aspire to and aim for.