I can guarantee most of that difference comes from the fact the hd600 is open back and not the frequency response. I have tried headphones with similar frequency response where people claimed there was a substantial difference and there wasn't.
The shure srh840 vs srh750dj.
Is it true there is more bass? Yes but it's not hugely audible unless the track you are listening is huge on the sub bass. Everything else on the graph is only off by at most 3db and i hear no difference.
I took it another step further. I wore both headphones at the same time. I put a shure srh740dj pad on my left ear and a shure srh840 pad on my right. There wasn't enough of a difference to warrant any discomfort in listening.
Point i am trying to make is am very skeptical of a lot of this community. People tend to recommend headphones which are popular over what they have tried and they say things which are innaccurate. I am not saying your wrong but i am still very skeptical there is a huge difference between the hd600 and shure srh940. Judging from that graph however i would think the hd600 would be really harsh.