My props arrived, very quickly actually, considering they came from the US.
The threaded 'nut' is not an integral part of the prop but is secured in place and can be moved slightly. Difficult to tell if its metal or plastic without scratching the surface, which I don't intend to do.
The edge of each blade tip is curved upwards slightly.
So far I've only done a hover check of the new props in my back garden and can't say I noticed they were any quieter than the oem dji's.