Yep, Dave, I considered that. I understand that there are some people that get shaved necks to flatten out the profile, and I would opt for that to compensate with either radical design. The overall neck thinkness would be exactly the same, I think, as if the ebony weren't present. Instead of say, a 1 thick piece of laminated maple/PH, you'd have a 3/4 think piece of laminated maple/PH with a 1/4 ebony cap. Maybe 7/8 and 1/8. I think the ideal thinkness for the ebony would be an exact match for the thinkness of the top, whatever that is, so they'd line up below the bridge at the bottom of the body. I thought it was 1/4.
A full-length ebony cap would give you an approximation of bookmatch-to-center in that there would be no neck showing through the front without the careful hand-fitting of the top that option usually requires. It would also give you more ebony in the neck which might further reinforce the fundamental and sustain. Finally, it would give you a really cool look down the middle of the bass with the solid black center and pickups sticking out a bit further here and there. It would probably be really impressive with a flamed or quilted maple top, though I prefer darker top woods.
The questions are: Would the neck be strong enough with the laminated pieces made that much shallower? Would it be cost-prohibitive? Would it add to sustain and fundamental the way ebony laminates do? Would Alembic do it, or better yet, have they ever done it before and what happened?
That's if you ran the ebony end-to-end as a cap for the neck. If you just thickened up the fretboard, you could probably shave the back of the neck a bit to compensate as well. The thickness of the ebony there would be less of an issue since it wouldn't have to mate up with any other laminates. Here's where you get the slap advantage by raising the fretboard a bit higher relative to the top. I doubt this would provide as much an advantage in tone versus a full length cap, though it still could do something.
In either case, I wouldn't want to compromise neck stability. I enjoy fiddling with setup from time to time, but not on a nightly basis. I still want enough meat to the neck for it to hold a setup.