I want a pair of HD650s pretty badly, I heard a pair at a meet and really enjoyed them.
The only thing I will warn you about is soldering the drivers. I have never had it happen but some people have heated up the soldering points on the driver too much and the voice coil detaches, so just be careful.
They're so nice. I will get another pair eventually, I loved them!
Thanks for the heads up, I just got the "ready for pickup". I should be ok, if not then it'll be a hard lesson haha.