Not to be mean but i'm having bad thoughts about this idea. I like how your considering Nexon and the safety but please consider the economy. Yes, you are technically right about selling adv play items as Nx for gold, but those are just small increments that varies with how useful the item is. Now a dye goes for about 12-15k now. A advance feather, which u can buy 3 of for the same price, is about 20-30k total. Now think about selling $10 worth of nx which u can do whatever you want with it.
- players will start making a price, which will throw off the economy of adv paly items unless they base the cost off the most expensive Adv Play item (adv feathers or dyes).
- The general mabinogi economy well get thrown out of perportion just because of everyone being rich.
- This game's money system would be basically:more $$$ = more gold.
Besides of the few things I've pointed out there is propably a ton of other things that would happen. My best bet is that the new comers without Real life money will die off because they can't keep up with the prices and everyone else.
Just my opinion~ (Excuse any grammar & spelling mistakes =D)

good times....
Well its tiem to move on :O