I had a chance to play this creature only once. Its' construction is similar to shortscale Les Paul. By the way, [fretted] shortscale Gibson LP basses are also a very tricky thing. You can get a cool vintage sound with flatwounds, with muted highs and sustained low-mids, but it won't play heavy metal or funk. No slapping.
Diamant bass is, for sure, a pretty soundless insrument. The shortscale construction don't produce too many lows, and original Jolana pickups reproduce dull mids only. I've heard a band where bassist used this bass live - it sounded like an old shoe. A muted, midrangey sound. It can help a lot when shooting a video with breaking guitars. It will also work in a beginners' school band. If you still want to buy one - don't pay more than $50!