Here's what the No. 1 nib looks like in the pen and a writing sample. Definitely a winner. The bottom nib is a Delike art / bent nib for comparison.
The section, feed and collector are interchangeable between the 601 and 618.
Yep, I agree. That nib is fantastic! I prefer it's smoothness and wetness to the 12k fine nib in my other 601.