I own and play a fretless six. It came with round wound strings, most fortunately, as I prefer that sound and feel on an electric bass. I do own a set of flats, not installed, that may one day end up on my bass, but I am satisfied with the rounds enough to keep them is a bag for a very bored day when I absolutely must string an instrument for no good reason. I would not be surprised if that bag remains unopened for the remainder of my life. My inventory of rounds is regularly used and stocked. I haven't seen any wear on my fingerboard from the rounds. Even though I have my hands on the neck of a thing, I have no desire to crush it in my fist and found that death-grip fretting hands don't lend anything positive to the playing experience (slower fingers, decreased stamina, increased wear and tear on everything involved). Also, why scrape a string against the neck sideways when you have no frets and can bend any note as far as the scale will allow?