I received my NN3 MKII with the RD16 base, late last week. My plan was to use my existing Acratech GP ballhead as a leveling base. The fly in the ointment, is that both the ballhead and the RD16 base require a 3/8-16 threaded stud, and no one really offers such a accessory (since both the RD16 base and the GP ballhead only have a female 3/8-16 threaded mounting). Right now I am using a camera plate and its quick release base along with a 1/4 - 3/8 screw adapter to attach the two major mechanical components together. [The problem with this assembly is the rear lip on the camera baseplate is not flush, thus the RD16 is not sitting level, therefore requires additional leveling.] I was planning to the camera plate and base on my backup camera. It would have been nice to be able to just find a plane 3/8 -16 threaded stud about an inch (maybe an 1.5 inches) in length offered by someone to simplify the connection process. I can't be the only one who has run in to this connection problem. Standard leveling bases come with a 3/8-16 male threaded stud as part of the base, that solves this problem.
I do have to say that once assembled, the NN3 is very easy to operate, and is much more accurate than what I have been doing (by hand and eye). It speeds up the process greatly.