Okay, I'm going to go against the grain here a bit... I would not get both the Anthracite City and the GH Work. I know GH makes a big difference, but unless you have unlimited funds, I bet there is another colour (out there now, or waiting in the wings to step up) that will grab you. I would personally diversify my collection more than just opting for two Anthracite bags. I've had the opportunity to buy some really great bags that I just had to turn down because I already had the colour in something else. I can't seem to justify having two bags in the same colour, even if one of them is just a coin purse or Makeup, because there are so many other colours out there I want to have.
In the end, though, it really does come down to you and what you will use and love...