Lots of excitement after all these years!
I have both and use both.
Pelikan M1000 nibs are borderline unusable due to wetness for the line width is many cases, and you can only choke down the flow so much with simple modifications. I just use better paper and it helps. I find them brush like in their softness and sometimes describe them as mushy. It is different than any other factory nib I have tried. But I like the old oblique nibs they no longer make so I keep a few around. I also have a fee modified and retipped for more interesting writing.
That Sailor KOP in ebonite is a better fit for my hand and the specialty nibs are a real pleasure. The regular M and B are fine but the Naginata nibs are real fun to write with, especially the Cross Point. A cartridge solves much of the ink capacity issue.
For most people the Pelikan is probably a better fit for ink capacity, reliability, and cost used. Nib swapping is a great feature for those who use it, and if nothing else it makes cleaning a lot faster.
If I could only keep one, it would be the Sailor KOP in Ebonite or urushi. I can always get a custom pen made to utilize my M1000 nibs.