A couple of years ago Steam announced that they had 125 million users and now they are suggesting they have 11-13.5 million concurrent users.
http://store.steampowered.com/statsAs crazy as it sounds, I am not in favor of a steam move. From what I can see, instead of paying a sum for advertising, Hitech will have to pay much more over a longer period of time with Steam supporting some of the burden. Worse yet, Hitech will have to abide by policies that Steam demands, including returns. So, does HTC want to pay a large sum now or pay a larger sum over a longer period of time? I'm not in the game building business, and I am not qualified to decide.
Regardless of the decision, I would recommend deciding before the new Band of Brothers series based on the 8th AF is released. There will be a fervor, a resurgence if you will, in interest in WWII and particular in WWII aviation. Just like the original interest in the genre when Band of Brothers was released, in fact it may have made the Call of Duty franchise successful. I would strongly urge that advertising and/or Steam subscriptions be started just before interest in this genre is at it's zenith.