I think it’s early days ref ND rust. Given the general lack of rustproofing at the factory, and the recent change of tactics regarding “not guaranteed against road salt corrosion” it’s probably fair to say that at some point, if neglected rust will start.
May be an idea to be as new as possible and get it treated by one of the many specialist if you intend to keep the ND for a while?
Another point to note is that I would imagine the ND is a different animal to the NC?
We have owned a Mk1, Mk2.5 (for 17 years) and only recently changed to an ND. We gave the NC a miss for no other reason that we loved the NB and were just about getting our heads around changing it for an NC when the ND came out, and to be honest I just preferred the looks of the ND. The ND seems significantly smaller than the NC so may be worth having a test drive to see if you can live with the lack of space first?
…happy decision making!