Ahh, good catch @Christopher, 4.X oz per shoe not pair. The NB website didn't specify if it was per shoe or pair. Maybe all their weights are by shoe, which would be weird, but as you show it seems to be. Anybody know for sure if that's NB's practice?
As for durability, most of the reviews I've read and the posters here seem to concur, that they are not very durable. Which means about 250 miles as opposed to 500 or so for a good trail runner.
Also, the grip is an issue with the Vibram patches. In tests at irunfar, they determined the Merrell Trail Glove to be the best zero drop trail runner in terms of grip and durability.
But I must say, NB takes the cake on sexiness, style and lightness. Most of those points are not all that valuable on the trail though.
I'm interested to see what @Chris Wallace comes up with in his review for BPL.