Sorry I'm late to the thread, I know, flog me later. Nearly all of my headphones, save one pair, are all closed back, including my all-time favorite the AH-D7000. My only experience with open back was the first AKG-701, and I did not like them at all, due to the lack of bass. That is actually what lead me to my D7000 purchase.
However, as the years have passed, and I have educated myself a lot more on the matter, and came to understand I wasn't comparing apples to apples, and my expectations should have been different. Imaging and soundstage is what one should be primarily concerned with in an open back headphone. So, I just ordered a set of Focal Elex off of this site, based on the recommendations of others, and am looking forward to the expansion of my auditory horizons. Apparently, it not only does imaging and soundstage tremendously well, but it also has incredible bass. Will it supplant my D7000 at the top of my list? I do not know, will begin finding out on Monday, but I can tell you right now, that will be a tall order, as I plan on being buried with my D7000.
In all honesty though, the never ending pursuit of the next "best" sounding headphones is what brings us here in the first place, isn't it?