Cosmic Cobalt is an ink that I've always been tempted by, but I've always put it back on the shelf. It don't care much for purples, and this ink is right in the blue/purple divide. When it's wet it looks like a purple, and when it's dried it is much more blue. I had it in a Kawaco Sport with a broad nib, and it was a bit wet. That is a wet nib, though. Cosmic Cobalt was pretty well-behaved on most papers. It was a little bleedy on cheap filler paper (which is sub-office-quality paper), and there was some feathering evident, but it wasn't all that bad. It would behave really well with a less-wet nib.
Here's the video review. You'll notice that the ink looks much more purple in the video. I don't know if that was a trick of the light or just the lense on my iPad, but the color in the still images above is more accurate.