I guess you already know that the NN5 is a very versatile product.
Although the swingarm is suited for long lenses I rarely use the full length of it until recently.....
With a QTop quickmount mounted on the camera adapter of the swingarm I can make a nadir patch very easy and very fast.
All I have to do after I shot the roundshots and zenith shot is to swing the camera outside the NPP position to the front position, turn the camera in the QTop, shift the camera adapter to the end of the swingarm and take the offset nadir shot(s). The QTop has 12 fixed positions so it is easy to turn the camera 90 degrees for the offset nadir shot.
I can choose to shoot from the same tripod position or to move the tripod just outside the original position.
When the tripod is not moved then I have to retouche the end of the tripod legs out of nadir, with a repositioned tripod the offset is much larger and it can be more difficult to patch the nadir shot but then retouching is not necessary because the legs are masked out. My preferred method is to replace the tripod just outside the original position.
Of course it is also possible to use a QTop with a NN3 but the swingarm of that model is shorter so it could be that the offset is not enough to cover all the space between the tripod legs with 1 shot.
If the tripod is repositioned just outside the original position then there is no difference in the results between a NN5 and NN3.
Some extra info about the use of the offset nadir shot position