I have two BTBs.
BTB1835, premium line, Aguilar pickups.
605MS, workshop line, T1 pickups from Ibanez.
The 605 workshop line is actually configured just like the premium line, but simpler (and cheaper?) woods
There's a music store near me with a SDGB1.
It is indeed just like the premium line BTB but with sweepable mids rather than a 3-way selector.
It played as well as I expect from my fretted BTB experience.
Ebonol board is very hard and has a more 'fretted' quality to the sound than other fretless basses I've played.
I can echo that it is absolutely able to cut through in a mix.
The longer it remains in store, the more likely it ends up with me.
It's the same size as the 1835, so I can say it fits in a Gator G-PG case.
Ibanez MRB350C and MRB500C will also fit it.
Honestly, it's not too hard to find other cases that will fit it as well.