Are those the premades with full 346 (heroic) gear? I've encountered a few of those. Pretty funny to see someone in that gear without ever seeing any of the normal instances, but ok.
I'm at the 329 level now, so i can start doing heroics. But i won't yet. Still wiping plenty on bosses (and sometimes even trash) in normal 5mans, so i doubt heroics would be a good choice.
I'm sticking to my idea that, if this difficulty will go live, we'll see a LOT of people struggling in 5mans for a long time!