h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

One additional advantage the electric fretless has over the electric fretted bass is the ability to sound remarkably more like an upright bass, without the need to transport a 7 foot piece of wood. The classic walking bass lines of jazz standards, in, say, a trio or quartet, have a characteristic intonation that, while not A440 accurate, give life to lines that reach up the fretboard, a melodic strain of sorts. Between tone and tuning, a jazz player could be equally comfortable with a fretless electric bass or an upright.

here here! Good point indeed!