Best level to do ZF?

I was thinking 44, just because of the Cloth Helm and Caster Staff that drops. However, quests..? Are they shareable? 

Karik wrote:Healers don't follow this rule. If you've got the gear you can be a few levels lower.
Bioness wrote:I can somewhat agree with this, although if they pull proximity aggro with a skipped pack or at constantly running out of mana, then that would be a problem.