The nuvinci weighs 4,200g (according to QBP) and costs more than twice as much as a nexus 8 hub (at my cost)
On a bike like this, weight isn't too much of a concern but since I'm a roadie, i really don't like the idea of doubling the weight of my bike with just the rear hub. I'm building this cause i dont want to be riding my Record bike to class. Also the cost and unproven longterm durability