I caved and got the HD700 new from Amazon. Currently listening to them and find them very smooth, no fatiguing treble or harsh "ssss" as of yet. I like the sound.
However, the build is a little poor considering the price. I've already slightly dented the grill on one cup as I was trying to get it on my head. The grills scuff and dent too easily. The build quality is not up to scratch compared with Ultrasone and Beyerdynamic.
Apart from that, enjoying these thus far and will run them in for a while.
You just have to be a bit more delicate with them! Mine are still mint. They are a precision instrument, not something to manhandle...