I am a fan of Valve and steam, however if the original poster is concerned about buying DCS online, all I can say is that it was pain free, easy, fast and secure for me. I had no problems and believe me, this sim is a blast. As for DRM, not much you can do about it, but for the record I've had no problems with starforce either with DCS or other games in the past. You'll cave in...
Edit
http://www.simhq.com/_air12/air_394d.html published on 9 Dec. 2008. Suggests that a steam version may be the works, but no confirmation.