If you do a Pilot mod to the Ahab (look up 'Ahab Mod' ...by cutting out little half moons on the nib, it will take an Ahab from a hard semi-flex pressure....superflex...in it does flex enough to qualify, to a much easier to use first stage super flex, what I call an Easy Full Flex. I have a number of pens with that flex. ***
I have three wet noodles...two are 52's....one starts out as an Easy Full Flex that gets much easier then as a wet noodle half way through. The other is ok, but both don't match my Soennecken superflex.
A Soennecken dip pen nib is like many, is more expressive than any Zebra G nib (from my reading the Zebra Z, is on the lower side of flexible dip pen nibs) .....and is better than my best fountain pen wet noodle. It's sort of medium...I have a few more of them.
A Hunt 99-100-101 are the real wet noodles (flex when there is an earthquake in California) .... the Gillette 303/404 have great reputations also for pure flex.
Not all '52's are wet noodles.............in fact a fine poster posted what Waterman said in the 30's, they were after tine bend, not tine spread, looking at a 3 X a light line tine spread..............so many of us are spreading the tines more than designed.
So looking for '20's or before pens might get you more......""""I have two wet noodles - a Waterman 14 and a Waterman 15, both vintage pens from the early 20th century and costing about $100 - $150."""
There is much variation in superflex......the more you have the more variation you will meet.
I did run into a '20's MB Safety Pen....now that was a Weak Kneed Wet Noodle.....
The thing about '30's and before nibs, is they can be lumpy, chunks can fall out, in tipping wasn't perfected until in or about WW2. So I'd not try to smooth them. I don't have a link file, but perhaps some one can link you to that post on this com, that links to that lumpy nib study.
*** I have a subjunctive flex system of 1/2s. I've stated it many times. You can find it in many posts,
If you can't find it, I'll do it again.
With superflex it's more helpful to those just entering, and not to those with 5 or six superflex pens...especially the wet noodles.