The general consensus with Diamine Registrar's ink is that it can be hard to clean, so I figured I would test that theory. After writing up my review, I left the ink in my pen and converter for about a month without touching it. I picked up the pen and was able to write with it, so it hadn't dried up; though the big test would be trying to clean it out. I emptied the ink out of the converter and immediately noticed that it had stained it (I couldn't capture a picture that showed it well unfortunately). I went ahead with my normal routine and cleaned it with water, and it didn't budge. So I grabbed my Goulet pen flush, filled the converter and let it sit overnight. The next day the staining was gone, to my surprise. I was impressed with how easily it came out, despite how long I'd left it sitting in there. Not sure if that's a bigger testament to the ink or the pen flush, but I'm inclined to say a little of both.
All in all, I really enjoyed using Diamine Registrar's. It behaves really well on most of my papers, even the cheaper stuff. No feather or bleedthrough was apparent, but dry time was a bit on the long side at 20 seconds. Like some iron gall inks, it does have a distinct smell that's quite a bit stronger than the Rohrer & Klingner inks. I didn't find it overwhelming with normal use. I don't know that I would pick up a bottle of Registrar's just because of it's tendency to stain converters, and lackluster color. I definitely prefer the R&K inks to this one, and I think Salix is close enough in color to be a suitable replacement. Nonetheless, it's still a good ink; so if you'd like to pick up a bottle, you can get 30mL for $16.95 or 100mL for $33.95.