The M250-C47E was talked about at HAI Heli Expo back in 2013.
Destined for the MD540 - i.e. 6 bladed 530.
I first saw what became the 540 back in 1997.
It was in the "skunk works" hangar which we were not supposed to see.
They must have been flying the 600N rotor as a test vehicle maybe?
Having flown a 600 a fair bit I don't think it will be all that it is cracked up to be.
Starting with the same basic blade and just adding more is not so efficient or optimised.
Lipstick on a pig.