I don't doubt the Steam pre-order will be up, but if it goes anything like Sengoku it will be up feb 6th at the earliest. Now if one considers the options:
If we pre-order from Steam.
-We get the DLC.
-It will pre-load and unlock at 9am PST on feb 7.
If one pre-orders on Amazon or gets another boxed copy.
-The game will ship feb6, you'll have it 7-8.
-The game registers on Steam, the box and dvd can presumably be tossed.
-The game is effectively half-price, but comes without the DLC
Pre-ordering on Amazon is cheaper, but you might have the game a day late, and you miss out on dlc. Another benefit though is that you can stop worrying about reloading the Steam store every 10 seconds for the pre-order.
Every single game I have pre-ordered on amazon turned up on time, except EU-rome - they emailed me to tell me it was out of stock so I bought a download. Besides, they're listing the dispatch date as Feb 1st, which means it will turn up very early.