The Stealth Passenger Plane- You wont hear it coming till it crashes into your buliding

The BBC today reported plans for a passenger plane with roof mounted engines and a 'Delta Wing' design, for a quiter, more manoeuverable, more stable and comfortable plane. Hmmmm....... so the airlines can send up more flights becuase there wont be complaints about the noise, and the plane can execute rather tighter manoevers so Air Traffic Control can juggle more of them in the air at once over the airports . I believe the collective noun for these planes will be 'skyfull'.
Assuming they show up on ATC radar at all, obviously.
It'll all end in tears I tell you.