Sometimes? This debate over rounds or flats on a fretless is a little off putting. Your technique determines fret board wear and the string choice, be it round or flat or in between, has a lot more to do with feel than sound. I been playin fretless instruments since I first picked up a Cello in grade school. All fingerboards wear, no matter the string choice. I use rounds, all my life, because I never heard a fretless player that influenced me that didn't use rounds, except maybe Bill Wyman. Boz Burrell, Jaco Pastorius, Tony Franklin, Gary Willis, Roger Waters, Marco Mendoza, Richard Bona, Michael Manring. All these guys used rounds. So I do. The marks on the board provide a bit of air under the string, the string wants to vibrate freely, and it will create room. After the initial marks appear when playin a new, or reconditioned, board? They don't necessarily grow. Proper vibrato technique, raising your action, can help to make an uncoated board last longer. But? I play HEAVY music, I play wit reckless abandon. I play 250 dates a year. And I haven't had to recondition any of my fretless basses yet. Coated or uncoated. Rosewood or ebony or purple heart. I slap. I dig. I kill my basses. For a brighter, more defined sound? It has to be rounds. It was suggested to the OP to look to the tones and players whose sound you admire, and do what they do. There are a million hacks surroundin us, tryin to tell us bs over this and several subjects, without the raw experience to actually make a determination. Look to guys you admire, the guys that motivated you to like fretless to begin with, and do what they do. Here at Talkbass, resale value is held in higher esteem than tone, in many cases. Science tellin me what my ears should hear. My heroes would never accept that. So I don't.