I have a somewhat different perspective regarding the “classic” versus “modern” comparison. For me and of course it is just my personal viewpoint, the 5231 is more classic. I say this because, the font is more traditional, there is no crown guard and Patek Philippe is on the dial not on the bezel. Most important for me the overall look makes it seem like a modern derivative of the historic and uber rarer Ref
2523 world time. I attach an image.
Of course what I write is just my opinion, no more - no less.
Certainly our 2 viewpoints can easily co-exist and having them makes for an interesting discussion. So many thanks for your response. Best regards, Patekova