I've been testing both ink samples and inexpensive Chinese pens. Yesterday I put some Private Reserve Lake Placid Blue into a Wing Sung 6359, and today I inked a Moonman 600S with some Pilot Iroshizuku Asa-Gao.
I wasn't really thinking about them being similar colours. I've been working my way through the various Private Reserve blues, and today something reminded me that I'd been meaning to look at Asa-Gao.
I was amazed to find the product of these two pen-and-ink combos to be virtually identical. And so I did an off-the-cuff side-by-side comparison on a page in an A6 Leuchtturm 1917.
You can see some differences at the top of the page, but nothing that couldn't be explained by the Moonman laying down more ink. Both pens have F nibs, but they're different nibs from different makers.
The lines of text at the bottom were written alternately with one pen and the other. I find it hard to see any difference at all.
Nothing remotely scientific about this. Just a doodle for my own amusement, but I thought the result was interesting. The image is an iPhone snap under artificial light after some rudimentary photoshopping.