When the addition of a second currency is introduced, you are destined for an unfair world. You have paid for the game, maybe for a monthly subscription because you admire the game enough; but when you have to pay more just to get stuff done within the game, something isn't right. Just imagine the less well-off gamers wanting to play a game they have saved up for, then they get they're ass kicked by some spoilt teenager who gets money handed to him on a gold-plated tray... There should be and in-game currency and an in-game currency only... you earn what you put in... don't just buy your way to success.