Once, in the mid 90’s (?) while traveling, I bought a felt tipped “brush pen” and was really disappointed with it; probably because I had big expectations of what an item like that should be like. A few years later I stumbled on a Pentel Pocket Brush Pen and was both enchanted and somewhat disappointed. If I remember right it had a few ink flow issues, or at least I thought it did, and it wasn’t that great on some of the watercolor papers I was carrying around at the time.
That said, a quick glance at some old sketch books shows that in the early 2000’s I went from mostly sketching with a pencil, to mostly sketching with a brush pen.