BoulderBill wrote a review of Kuat NV 2 Bike Rack on April 6, 2014
Familiarity: I've used it once or twice and have initial impressions
Just put the NV and the Add-on together. Took longer than I thought it would. I'm a dork I guess, but the pieces are all pretty heavy and it takes a while. With both racks joined, it is heavy. I can maneuver it myself and get it on the hitch. Once on and screwed tight, it seems bullet proof. It is certainly the most attractive bike rack I have ever owned. I think this is going to work out very well.
Some slight detractions. It must come off for my garage door to shut. This is quite a bit of on and off every time I want to go for a ride. It makes my back up alarm scream! :) The conversion form 2 bikes to 4 bikes is not fast. I might, as others have noted, add a single tray for roof mounting just to accelerate things. It is very expensive and, again, heavy.
But all and all, it looks to be a very solid purchase.