Wow you just missed the special on steam a few weeks back, That's when I picked up my copy... got the whole trilogy including everything so far.
Had to wait a bit to make it complete, I placed the missing DLC's in my wish list and wasn't long before that went on sale too.
If I had more money, I would have bought it at full price, really great game...So much content and now that it is better compressed file format, its even better.
(160+GB's VS 66GB)
I'd def go with the steam version for ease of use, amongst other benefits.
HiTMAN Trilogy + all the correct DLC packages, I'm going to be occupied a long time progressing to 100% it, even if this new content for purchased version continues to be released in the future.
I am also thinking that absolution style hitman works best for few days or less worth of a blast of continuously progressive gaming, and builds momentum much better for the gamer.