Dunno how did I missed this thread.
100% this game some years ago, and I liked the shared achievements feature with Xbox Live. But if I learned something from japanese developers, it's that I will have to unlock everything again (good), and will have to pay as much as every newcomer to get the full game on a random sale.
Deus Ex already spoiled me.
You will probably have to unlock everything again, but I doubt you will have to pay as much as every newcomer to get the full game. You'll get the full game from the start, and it looks like DLC will be a separate purchase.
Also, fwiw, Dark Souls recently got ported over to Steam and it had a save transfer method which is cool.