Being unable to find an inexpensive pants-pocketable M nib fountain pen to my liking for EDC, I'm considering a roller pen.
I know nothing at all about the brand and cartridge ink options, but my favorite gel inks are Uni Ball 307 (0.7) black and Uni Ball 207 (0.5) green-black and brown-black. I find that they are smooth, dry quickly enough for my lefty handwriting, and I want a thicker 0.7 line, possibly even going up to 1.0.
My first thought for an inexpensive knock-around pocket roller pen is a Kaweco Sport. Should I consider anything else for the pants-pocket in that price range? I like the look of the Retro 1951, for example, but I'd prefer the protection from a pen with a cap. (Safaris are out because my lefthanded writing style doesn't get along with triangular grips.)
And although I could try a roller ball eyedropper conversion I'm interested in learning about cartridges that can give me the same light touch, smoothness and dark thick line as the Uni Balls I'm used to.