As some of you people might be aware I purchased my Dumas set from NIBS.COM, given the opportunity I asked John Mottishaw to add some flex to my Dumas.
Here are the writing example of the nib compare to stock nibs in my collection.
All pen are filled with Aurora Blue ink.
As you can see the Dumas writing example is much more darker than other ones. Because of the flex it increased the ink flow and resulted super smooth nib. The only down part is I have to fill it often and the ink sinks through the paper.