I just purchased a used Pelikan 800 with a VF nib. I also have a 605 with a VF nib.
I was surprised a the difference between these two nibs that are supposed to be the same size. The 800's nib is thinned than the 605's.
I guess it's not really that much of a difference. But, it just feels different while writing. The 605 actually feels a bit smoother, while the 800 nib has a bit more "bite" bit is thinner. To me the 800's nib feels more precise.
Tom