When should I use Moonkin form?
If you have spent the talents to earn this form, you should use it as much as possible. Remember that moonkin cannot cast anything but offensive spells, and remember that you always have the ability to shift out into caster form. If you can afford to not heal, you might as well be in moonkin for the increased survivability and crit chance. It only takes a second to shift out and cast a heal on yourself, so always remember you have that option.