Was given a set of Cokin Nuances from Cathy Photo a couple months back to test out. Been playing with it quite a bit but never got a chance to sit down to write an entry for it.
Used Cokin Z-Pro series holder a couple years back when I was using grads. I stopped using them after getting a d800 and could get most pictures all in one shot or I would do a quick blend with masks. Hence haven't used the holder much. Back when I used grads, I took most shots on a 16-35mm and they produce a non fixable vignette at 16mm and correctable vignetting at closer to 19-20mm.
I tried to make some adjustments to the filter holder, by unscrewing and adjusting the holder so it only takes 1 filter rather than the 3 slots that it allows. This still made a vignette at 16mm but pretty correctable at 17-18mm. I will add some pics of the change I did to the filter later. Recently, I mainly used this filter at 24mm.
The copy of this filter i got from Cathay Photo was 10 stops (2^10=1024) meaning a 1/1000 sec shot with the filter will be about 1 second. Meaning you can acquire a longer exposure. so normally if you were trying to achieve a longer exposure you would lower your iso to the lowest say iso50 and change the aperture to say f/22 (However, causes diffraction and would make your picture look soft) and that would probably be the limit to how long your shutter speed could go. You could then add a ND filter to extend this exposure time.
With the filter on, you probably will not be able to see much in the viewfinder if you looked, so what I would usually do is focus first and take a test shot. Using this exposure time, i will multiply 1024 to the time and flip it over to manual focus and insert the filter on the holder and change my shutter speed accordingly. Whenever I add a 10 stop, I am usually trying to blur the water or streak the clouds and I would usually go for a longer exposure.
While testing it, the filter has a slight correctable magenta color cast. There's is no light leak when used with the Cokin Z-pro filter holder, the holder has a stopper at the bottom and will also prevent the filter from falling out in the other direction. All in all I think it works really well and according to google a set of Cokin Nuances 10 stop will cost less than getting the Lee filter big stopper. Value for money! I will add more pictures and thoughts along the way as I get through processing them but here's a couple for a start.