I would assume 1-85, it would be a total rip off for how much they are and how hard they are to obtain to only work the last 5 levels. I plan on just using the ones I have for 1-80 and if they don't work ill just replace them with questing blues.
It's 1-85 and I know because I have tried them out on beta.
You only need honoured rep with your guild which I got on a char playing from level 25-50.
I even mostly leveled through dungeons, so I'd say getting the new heirlooms is really easy.
Last edited by Subliminal; 2010-11-15 at 09:47 PM.