I just bought the 100-6 and I would say it is a very good helmet. I was amazed by the ventilation system, very pleasant and efficient. The weight is not noticeable while driving and it isolate well the outside noise. As always with the Nolan helmets, it's very comfortable. To get something (not much) more you have to switch to the Schuberth C5 or Shoei Neotec3, which however cost much more.
Have a N100-5 and all i can say is it's build quality isn't so good the sun visor after awhile will start to jam at the start so pressing the quick release button to return the sun visor will not work and also the helmet is very heavy after 30 mins of riding you can feel it's very heavy especially when turning your head to check your neck will feel sore . The 2 buttons to open the helmet sometimes can be quite troublesome and would require a bit more force sometimes . The designs are quite horrible imo just get a shoei
