Hi all and thanks Jazzyvee for the invitation.
The bass in the image provided by David is mine - it's a Walnut Burl top as Jazzyvee suggests (and I think it's the 'example' bass for such facings on the Alembic pages).
I didn't spec the bass - this was done by the original purchaser (a good friend of mine in the UK) around 2007/8 when he ordered a pair. A fretted small-bodies short scale in cocobolo and the fretless in burl walnut. I bought the coco from him around late 2008 and then the fretless was offered to me last year (a long story).
One of the benefits of the walnut is the weight - the fretless is much lighter than the fretted (really, a significant reduction). It's difficult to comment on what might be added by the coco to a fretless. There's certainly nothing lacking in the walnut. The mids of the fretless are superb with a gorgeous bloom to each note. It's worth noting that I change my right hand position when playing fretless and play much closer to the end of the fretboard. On fretted, I tend to play between the pickups. Changing playing position probably affects tone much more than the timbers in the bass. There is nothing that I would change in the construction or spec of the fretless. However, if I were speccing a fretless now, I may decide to go with a thick centre laminate of ebony. There's nothing missing in the lower mids or bottom end but it's an aesthetic consideration and may (and I mean 'may') add something to the already phenomenal fundamental. As you'll know the complex dynamics provided by the SII electronics imply that nothing is missed. A big slab of ebony in the centre neck position may just add more weight to each notes (but who really knows?) I may also go for more figured and flamed maple in the neck laminates but again, that's just aesthetics. If I can add any more, please just let me know (and good luck - what a wonderful position to be able to contemplate the commission of a SII fretless!). Thanks again to Jazzvee for the invitation