Very interesting, Stephen. I have (and love) the Naginata Togi (zoom / architect) nib on my Sailor 1911. I'd say Sallymander's pricing is very appropriate - especially since I cannot fathom the difficulty level in aligning the slits perfectly.
It's a PenBBS 323, for those of you who are curious. I think the Montblanc Curved Nib achieves something similar by angling and elongating the tipping.
Reminds me of (as an alternative) the "perspective nib" by Gina Salorino of Custom Nib Studio in LA. She did that grind for me on my Namiki Impressions with a very cool result -- like the Sallymander nib shown here, line width is angle dependent.
I think your pen used for display is a penBBS 323. Interesting nibs for sure but I at the point of getting used to writing with round nibs. Stubs are a whole other matter.