Well, the green striped Pelikan (no matter which size) is THE Pelikan classic for most fountainpen users. It was the one I was dreaming of for years until I got my first M400.
Never ever it would have crossed my mind to buy another pen than the green striped. Nearly 2 decades and several green Pelikans later I got my first tortoise 400NN. They are indeed beautiful. But the M400 looks boring compared to the vintage tortoise pens. And for some reasons I cannot explain the M400 tortoise (pre 97) shows some wear of the Stresemann the greenstriped M400 and the vintage 400/400NN tortoise do not.
Now I have a bluestriped and a redstriped M400, too. They are beautiful but don't see much use. My daily Pelikan is still greenstriped - or sometimes black - after all those years of Pelikan use.
Edited because I hit the return button by accident before I had finished my post