The conversion from fretted to fretless isn't too painful, but there's a little more to it than just pulling the frets and filling the slots.
The thing you have to take into account is that the loss of the height of the fret wire is non-trivial in setting the playing action - pulling them out is a bigger change to your neck geometry than any kind of normal wear. To maintain good playability, you have to lower the string heights a LOT at both ends of the string.
People have already mentioned that you will need to replace or rework the nut. If it's an adjustable one, you'll need to redo the top for the change to high-C, and you'll have to redo the bottom to lower the playing action at the lower range of the neck. This may be a little harder with your Alembic than most basses since the nut is brass instead of plastic or bone. You could route the nut slot a little deeper, although personally, I'd probably prefer to have the nut milled down (maybe it's easiest to order a new nut from Alembic!).
You should be sure to take a close look at how high your bridge is right now, as you'll have to lower it a LOT to maintain good playing action, possibly as much as 1/4 (5mm). On a bolt-on instrument, this adjustment would be trivial by shimming the neck, but for a through-body or set-neck this may involve changing bridge parts or inlaying the bridge deeper into the body.
Normally, you'll want the action low for more fretless mwah, so you want to make sure you can create enough adjustment range in the hardware that you can do routine adjustment without major surgery. This also means that you'll need to have a major fingerboard levelling (you'd need to do that anyway to finish the fret line inlays). A lot of fretless basses are cut with a ramp between the 5th fret and nut for lower action at the low range of the neck, but you may not need this if the nut is done properly. This sort of ramp wouldn't exist in the fingerboard of a fretted bass (although it might have been milled into the fret tops).
Finally, one other consideration for conversions... if you have marker inlays on the fretboard, I think they're normally shell on Alembics. If you play with roundwound strings, the inlays will probably get chewed up pretty seriously, as the inlays would be much softer than the wood. I notice the picture of the Orion on the product page doesn't have inlays, so maybe this isn't a consideration.
All in all, I don't think the conversion will be horribly painful, but it will be more complicated and expensive than if you decided to defret a Jazz Bass.
David Fung
