Hey, yer I read the same reports regarding cooling. I think it may be a little restricted due to the nature of the venting on the case but I have now upgraded all the fans to Corsair Air series fans. My CPU stays at around 55 degrees and motherboard is at 27 on full load, in a warm room!
So all in all the H440 seems fine to me for cooling purposes. Its a great case, and very nice too look, easy to use with lots of space!
Enjoy your DK2, mine should be arriving in July sometime fingers crossed, I cant bloody wait!