Yes, I think so! Especially this really great caramel brown, fittingly called "Karamell" from Octopus here in Germany. They have a huge web shop selling printer ink and toner and apparently one of their chemists thought he'd like to make some nice fountain pen inks too. They're offering a small range of colors at good prices, packed in the no nonsense Pelikan ink bottles.
|Nakaya Piccolo with Octopus Karamell ink|
I've also got Red and Burgundy. So far I've tried red, which is a pretty bright and not very interesting color and didn't flow too well in my Lamy 2000. The Karamell, however, is a different story. I love this shade of brown, it's quite light but easily readable, a little reddish but not too much and offers great shading. I compared it to Diamine Ochre, Ancient Copper and Montblanc Collodi and it's very different from all of them.
At first flow was very generous in my Nakaya Piccolo, then it dried up somewhat but still flows OK without any skipping.
I'll try it in some more pens as this is definitely a keeper ink! Will show the other colors as I test them.
The pen I'm using it in is a Nakaya Piccolo in yellow tame-nuri but fitted with a Platinum music nib as I no longer liked the soft fine nib the Nakaya came with and had the music nib around. As nibs and feeds were identical except for the imprints the exchange went fairly smoothly. (I've heard there's been a change of feed generations lately so this might not work if you have an old and a new model. Also music nibs have their own special feeds to supply both slits)
I have to say the Platinum nib looks great - I might even prefer it over the Nakaya ones looks wise.
The pen appears pretty dark in this picture so if you'd like to see some more of it look here: Nakaya Rainbow. It's the rightmost pen in the pictures. The color looks similar to shiro tame nuri but when held next to each other you can see that the base color is indeed yellow instead of white.