Hi Maxime,
This is very subjective. It depends on the style of music you play, how hard (or soft) you play the string. Do you use a pick? Do you slap the strings? What type of sound are you shooting for?
Personally, I like the strings very low. But I've had friends pick up my bass and have a hard time with it. Too low, they say. And for them, it is. When I first got my Persuader, I had to raise the bridge a little, but I've recently brought it back down very close to the fretboard. I have a much lighter touch (something my Skylark taught me)than I did when I first got the bass, so, now the strings don't buzz when I play them set up as they are. But when others play it, they buzz all over the place. I'm sure there are as many answers to this question as there are Alembic basses and their players. I guess what I'm getting at is, I have mine set up for my optimum playing comfort. It's taken a little time to dial it in, but it's worth the effort.
Now, when real bassists come along, they'll offer more educated advice I'm sure. In the meantime, I hope this helps a little.