No, because a full sounding open can trumps any closed can. Going from closed to open really adds ambience and immersion, not to mention usually better positioning.
The Pro 900 is closed sounding, no matter how you slice it. Positioning is between good and great, but they are considerably more closed sounding than say the DT770 Pro 80 or Denon D7000. The DT990 Premiums are more open sounding than the HE400, but sound thin and harsh in comparison. Bass is more preferrable on the 990s than the HE400 for my personal taste.
The HE400 have the perfect balance of openness, full bodied sound, and overall good to great positioning. They define all rounders for me.
I do need to use them for gaming a lot more to make sure I know what score the HE400 is going to have overall. Right now, I'm floating between:
Fun: 8-8.5
Competitive: 7.5-8
Yes, I'm absolutely in love with them, but I haven't had time to truly test out their positional cues outside of a few BLOPS games, and don't wanna blindly put up a score based on personal bias.
The HE400 impressions are gonna take awhile.