The idea of adding Moss is great, but enough time should be taken to plan the rates and items received carefully. This event was intended to be "gambler event", so every roll shouldn't be considered as win. If every roll gives you something valuable enough to be sold in the market it would just be an money making machine at first, and then eventually with time inflates the market with items that nobody wants to purchase.
Imo 10% chance for extras like toca, mbp, feather, crest etc. is way too high. Those are still the "top-tier" goodies for mid game gameplay and should remain their value as such. If people can get their hands on these items with only zen, those rolls should play the role of a "jackpot". I mean, would any casino hand out jackpots with 1/10 ratio?
Maybe you could add different category for each piece of equipment that's available from the Moss (helmets, armors, panties, gloves, boots). This way people could focus gambling on the parts they're lacking from completing their sets and it would reduce the anxiety of "winning" the parts they already possess. Also each weapon type could have their own category as on the original event, but still keeping in mind that it should be gamble, and not less than 50% of your rolls should be considered as loss.