More standard loot...especially at low levels you seem to get mainly money and mastery xp...and the occasional health crate or +% potion.
Gildings do not seem to be common in the blue boxes (or low level chars can not get them at all) ...had around 12 boxes now always blue box had around:
35000 to 135000 mastery xp
money
and randomly potions, imperial insignia and atlantean shards
So, if the purple box has not at least ALWAYS 1 gilding token in it, it will not be worth the work at all. Might be a good idea to make these drop even in the green boxes with very low chance. As already said, do not make this content work for people with more than a handful of chars. Or make parts of the drops (or the boxes!) accountwide claims.
where is a vendor or exchange npc for the atlantean shards? What can be bought with them?