I quite enjoy this ink. I'm on my second fill on my Ferris Wheel Press Brush fountain pen and about halfway through my first fill on my Noodler's Charlie pen. So my experience is fairly limited still, but I wanted to share my thoughts about this ink.
I love the colour, very much a grey-blue. Possibly a bit light for me, but it's very soothing too. Very nice for writing pages and pages of text. But I'm not so fond of it for my Bullet Journal or note taking at work.
It flows from the pen very well, no clogging or false starts. Possibly too well as the line it makes is significantly thicker than any other ink I've put in these pens. I'm going to try this in a fine nib pen soon to see if this makes the line size I like because with a medium nib, this line is too thick for my writing style.
If I twirl my Charlie eyedropper pen (cap on - of course), which I'm prone to do when thinking, then a drop of ink pools at the nib and will fall on the paper when I start to write. This didn't happen with Heart of Darkness, even when the body was less than a quarter full of ink. But it does happen with Blue Upon The Plains of Abraham, even when the pen is full.
I haven't had any trouble with it clogging or drying in the pen yet. But I use my pens constantly and a fill usually lasts less than a week.
After about a week, I was less in love with the colour. It feels a bit flat on the page, but that might be because the line is so thick or there's less shading than I'm used to.
Water test - I took some pages I had finished with and ran them under the sink for about a minute to see if the ink really was water resistant. The ink had been on the page for about 10 minutes so I don't think it was fulled cured, but very little ink came off. With some intense scrubbing I was able to get a bit of ink off, but the letters on the page stayed as they were. Eventually the paper started to degrade before the ink.
On the whole a good ink. Maybe with the right nib, this might become my daily ink. It's a very calm colour and I love the history behind it. I don't think I'll put it in an eyedropper again.