Maybe we'll get through this without the usual controversy over manhood and talent as manifested by one's preference for unlined or lined fingerboards. I hope so, anyway.
So here goes:
I have two fretless Fenders: a lined Standard Jazz and a Precision with an unlined maple fingerboard Warmoth neck.
If you need the lines, go for it.
Lines annoy me, which is why I ordered the Warmoth neck without them. It has dots where the frets would be -- but not at every fret, only at the positions that have dots on a fretted neck: III, V, VII, IX, XII, XV, and XVII.
That left me more opportunity than I expected to find alternate intervals in the music, so I bought a roll of pinstriping tape at Auto Zone and carefully placed small squares of it (.125" x .125") at all the "fret" positions. They are placed so they wrap over the edge of the fingerboard; they are nearly invisible a few feet away but in clear line of sight of the player.
I added a Sharpie black dot (the tape is silver) al punto where the exact fret would be.
The result is a clean looking fingerboard that still allows me to play in tune with very little effort, and, man, does it sound good! I've been playing it in preparation for an upcoming Make A Wish Foundation Benefit and I'm confident it'll do the job.
Godin makes a pair of fretless AGBs (A4, A5) with unlined fingerboards that have what appear (from the player's perspective) fret ends inlaid in the edge of the fingerboard. A guy at my church has one and it looks like the perfect answer. I just wish Warmoth offered an option like that -- I guarantee they'd be on mine.