I'm Portuguese and I have a huge respect for the NEXX brand.
I own a NEXX XR1R CARBON and it is, by far, the best helmet I have had ( I have in my garage a Nolan 101, a Shoei X-Spirit and a older Shoei Multitech).
Now I am looking forward to the release of the new NEXX X.40, probably will be my next helmet.
As for that one in particular, the new diablo one seems a peach!
DIABLO NEXX HELMETS
For the extra-price I think the carbon is really worth it! you can feel the diference at the end of the day in your neck