I like to think the fret lines more as "landmarks" than as positions you should put your finger on. I've had both lined and unlined fretless basses, and at least I noticed that I was looking at the lines or the side dots equally as much (as little as possible) when playing "normal" bass lines. It's the big position jumps where the difference is/was for me: with side dots I tend to always be a bit on the sharp side (due to the angle the neck is to myself). These transitions, for example to the high E on the D string from the lower positions, is much easier and more in tune with lines. This, of course, might be because I've only been playing the fretless for just close to two years, and "haven't just gotten it yet". But anyways, it is easier, at least for me.
And also, I really don't see the difference in looking at side dots or fret lines.
And also, I really don't see the difference in looking at side dots or fret lines.

