My buying experience was at Stereo, in Plaza Singapura, Singapore. They seem to have most stuff available for demo, and are happy to let the customer spend as much time as they want listening.
At first, I took the AD700s and AD900s for demo. I guess I would have been very happy with the AD700s, if I had not heard the 900s. The AD700s certainly sound great, but they are like listening to headphones, whereas the 900s made me feel like I was listening to speakers. I was using Mahler's 2nd symphony, played on my own Cowon portable, as my test piece, and, while the 900s could not build a real stereo landscape for me, as good speakers would, they gave a sense of space. Much more expensive: I asked myself, pretty severely, if I could really hear the difference. As objectively as I could, I answered, yes.
On recommendation from the staff, I also listened to Grado and Ultrasone 'phones. The Grado did not sound as good as the AKGs (but was still pretty damned good!)... the Ultrasones had a wonderful sound, but I did not like the on-ear fit. Sorry: I didn't note the model numbers.
I have never been a headphone man before. This is the first pair of serious headphones I ever bought. In the past, I have always disliked the sensations of weight on my head, and of being cut off from the outside world. The latter, of course, I got used to using ear buds when travelling, but still did not want to buy closed 'phones for use at home.
The AKG fit is nine out of ten. They are very, very light. They sit entirely around the ear (they are really big!); they are built for a head about half an inch higher than mine (I'll let you know the plastic surgery costs to factor in, after I get it done ).
I don't know if the velvet pads can be replaced. This is one thing I really should have enquired about in the shop but I thought of it too late. Quite how they are going to be for sweaty Chennai, we will see, but I think they will be better than more "clampy" phones would be. I am unlikely to be using them for multi-hour sessions anyway.
Yes, as already advised in the thread, they are noisy. I discovered recently that my wife can hear earbuds from across the room! To me, they are totally silent even three inches from my ear. We just have to hope the closed bedroom door will be enough in the night, when I will be using these things.
..day by day finding it sweeter.. sound isolation is good enough for a bus ride.. in case if its ok to have a long coild wire hanging in neck.. 
.. any way i never cared..its worth the sound...
