kachna96: Well, I wouldn't suggest going with Dark difficulty on first playthrough.
Firstly, if you want all the dark sets, you'll have to grind. A lot. The diagrams are pricy, the materials are pricy, even the crafting is pricy. + There is one easily missable item required for crafting the second set, sure you can obtatin it later but by that that time, it won't be worth crafting it anymore.
Secondly, if you want to play on dark only because you play most games on the highest difficulty, then go with hard difficulty, the only difference are the sets, really.
Thirdly, Dark sets are too OP whereas on hard, it's more challanging IMO.