I wonder if any of the bits from the stealth chopper recovered from Pakistan could be incorporated in the Z-20's development?
It was pretty thoroughly wrecked by the SEAL demolition crew, if the news photo and the account on "No Easy Day" is creditable in this regard, just a banged up tail section can't be of much use to the Chinese anyway. The part that the Chinese would wanted most - comm gear, engine and transmittions - are in the main fuselage and that part is in pieces, no good to anyone.
Other things goes, nothing the Chinese can't make at this time, alas a generation or two behind - sure, composite airframe and rotor, high performance engine are yet behind the curve, but still, stuff like NVG flight system and digitized cockpit isn't that new to Chinese.
Body work wise, there's a lot of guess work based simply on the survived tail section and that's where accuracy stops - the guesswork is what used by Dragon model and the props in the movie "Zero Dark Thirty". Now, the supposed "stealth" or "noise reduction features" are mostly dead weight and shaved a lot on the performance if you don't have the right engine to mate it with, which is exactly where the Chinese still fall short.