I also was a big fan of Neopan 1600, but never will buy expired ones. I still haven't found a real replacement for this great film. And these highest speed films degrade much faster than you may imagine. A Delta 3200 f.e. at the expiring date is already noticeably worse than a fresh one. I only buy them as fresh as possible.
And I totally gave up shooting with cams that can't be adjusted manually for the film speed. Not worth the effort imho.