If Nolan has gotten a size large helmet down to 1640 grams, that is a significant difference from the N103/N102 models, which weigh in at 1891 and 1850 respectively (size XL) Nolan uses two shell sizes...one for sizes XXS to L, and another for XL to XXXL, so there will be some difference between the L and XL regarding weight. Basically, Nolan has shaved off approximately 7 ounces of weight with the new helmet design. It also has some interesting ventilation innovations, and a new, lighter helmet chin strap mechanisim. Source: http://www.webbikeworld.com/r2/motorcycle-helmet/nolan-n-104/ There are some nice photos of the helmet in that article.
Duane...are you saying that the helmet visor does not have any detents, not even one for slightly cracked open? Does the internal sun visor slide (located on the lower left of the shell) enable infinite adjustment from fully open to fully down or is it on a spring that allows either up or down? That's not a huge deal, either way. The main thing is that it appears to come down far enough for the lower edge not to be a line of sight issue. The internal sun visor is one thing I really like on the newer helmets...the one on my Shark Evoline 2 works extremely well, though it could be a tad darker, but I think most of them are about 50% light transmission. Having that visor is HUGE when traveling anywhere that has dark tunnels to ride through (Blue Ridge Parkway, for example).
It sounds like Nolan has made some real innovations with this helmet.