As far as I understood, there's no more mesh north of N60? If that's the case, then a 50m mesh (Level 8 may also be compiled) is definitely an improvement.
I don't know how far north the AFS2 World can be modelled.
And a good 10m mesh already may provide very satisfaying results.
Last year I tried to add airports in Norway above the 60th parallel and was able to add a few but as I went further North I got a series of weird and distracting vertical lines from the surface to infinity.