I love drawing with a fountain pen! There's a richness in the ink as it flows from an actual nib onto quality paper. Lately, I've found it really frustrating when, after I bought an "art" pen, the ink would stop flowing mid-line and I would be forced to go back over the line and try to smooth it out, ugh. Not to mention "splotches!"
I found myself in Vroman's (my local independent bookstore here is Pasadena, CA), standing in front of the fountain pen cases, wondering if these pens designed for actual writing would be better than what I was using? I splurged and bought myself a small aluminum Kaweco pen.
Sometimes, you CAN blame your tools, not the artist! Incidentally, I love sketching in pen & ink because it's freeing exercise for more detailed paintings, etc. These sketches, largely portraits, are quick and easy, but sometimes a simple line can convey much personality and emotion.
Easily, one of the best decisions I have made, my little Kaweco, paired with a bottle of Noodler's Ink is such an absolute joy to use! The ink just flows so smoothly.