In the FWIW dept....here are the paths I have traveled with fretless.
I started playing bass guitar in 1970 at age 15; mostly Woodstock music, Chuck Berry, and British Invasion music - especially the King Crimson / Yes derivatives. Stanley Clarke blew my mind in 1973 with the RTF Soundstage performance in Chicago (it’s on YT); and I resolved to learn upright, starting with classical training. Being all in, I sold my car and bought an upright bass and a long scale Alembic LSB - which played / sounded nothing at all like Stanley’s bass. In fact, I pretty quickly had that bass defretted and put D’Addario Half Rounds on it, reasoning that I would get something like an upright effect with it. Jaco was by then blowing my mind; but, back then, I would admire the great players, but tried to forge my own sound.
Ultimately, I decided the reach to the lower positions on the fretless LSB was too much, and purchased a ‘75 Jazz Bass, and a Warmoth fretless neck with an unlined ebony board. I put round wounds on that bass, and played it for two solid years on a weekly basis as house player for an open mic Blues / Rock gig. In fact, I played that bass so much that I eventually wore “groove” spots into the guitar chord root position notes, and had to fill those. I also coated that board with Minwax polyurethane, which was outstanding, retaining warmth but allowing the notes to speak clearly.
I eventually removed that neck, and it resides in retirement in my closet. I didn’t especially care for the feel that the steel bars contributed. Also, I found that while the neck looked cool, large shifts into the upper register for quick fills suffered a bit from shift accuracy. Audiences didn’t notice the visual stuff, but the intonation thing mattered. So, I went ahead with a lined board, which cleaned up those fills for me, and made it a whole lot easier to play Real Book heads in the upper register.
I’ve been through a few other fretless basses, lined and unlined, since then; attempting to sort out what I wanted in a 5 string. I’ve eventually settled on a lined Zon Sonus Special 5 with a Pope preamp; and am pretty much done. It’s a great bass. I don’t find anyone cares about the appearance one way or the other; but, they do notice the intonation.
It is possible to nail the intonation thing by mechanical memory. Somewhere I’ve seen vids of a blind (I believe female) fretless player who absolutely kills it. So, it is possible, if the looks really matter to you. I’m too old to worry about that any more. In recent years, I’ve been much more absorbed by progress with my upright playing. For one thing, Jazz gigs where I can exploit the fretless bass guitar have become much less frequent for me. I wish that would change.
GL
and this will be the new one to replace it when it's finished
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