Personally, in my opinion, SOMETHING VERY TOP SECRET flew the team into the compound. I believe that "something" is a stealth helicopter BASED upon the UH-60 airframe. Do I believe it was a "bolt-on" package? NO
This project was built from the factory up. Probably ALOT of secret units were in on this helo. DARPA, Flight Concepts, 160th just to name a few.
Awhile ago over on the 160th FB site, an artist painting of the stealth hawk was posted and caused a ruckus amongst the members. Maybe, just maybe, someone slipped up and possibly started to let the cat out of the bag.
As far as retractable gear, Sikorsky already has RG helos in its inventory. The technology is already there. I'm sure alot of info was gleaned from the RAH-66 program.
Personally, I'd love to have a 1/35 scale stealth hawk. It would be cool to build whether it's real or not!