This Moonman clear demonstrator is my showy fountain pen with a lot of crazy colored ink of choice.
A few years back I bought a TWBSI Eco. I enjoyed using it and it became my black/red ink pen of choice. A color I used to use a lot of. I wanted another pen to fill up with some of the neat colors I've acquired over the last few years. The Moonman C1 is a great choice.
The tank is huge and it looks really cool when filled with a teal or something crazy like Noodler's Rome Burning. I also enjoy that I can fill the huge tank and write all day without fear of running out.
I enjoy living with out wonder as to ink level. My checking my beloved DuoFold involved inky fingertips.
The fine nib writes like a fine nib and flows ink pretty well. The Rome Burning is pretty soupy and can gum things up. I ran about 1/3rd a tank of it thru the pen and I didn not have a problem. You can unscrew the nib so I am going to assume there are lots of medium, bent and other nibs available. It looks an awful lot like the nib on my TWBSI, but I do not have the pen handy to check.