Thank you very much @bula. I did some further experimenting with your suggested settings, especially for analysing stars (3). Still need to tweak / further experiment with the settings. Whats happens is that at one of the seams I get double stars; see attachment. In the end I cheated and mixed two versions (with double stars at different postions) in Photoshop.
Now I can provide a link to the full size version (which is actually ~50% of the image at its native, true resolution).
http://www.mauricetoet.nl/Deep-sky/i-fQnSpV7/O
