this discussion about weight kinda brought back memories -
my first alembic was a fretless 4-string essence that i got brand-new from GC in seattle back in the late 90's. As i remember, it was a light weight, almost delicate bass, very easy to strap on, thin neck (i've actually got a picture of a younger, handsomer me playing it, not sure if i wanna post it). Fast forward about 20 years and a whole lot of water under the bridge. Now i own a 5-string fretless essence and while it's not the biggest or heaviest bass i've owned, she's a thick sturdy girl. the difference between the 4- and 5- string versions of this bass is striking. Thicker (and wider) neck, bigger headstock, heavier, definitely not the delicate flower that i owned back in the days of yore. I haven't put it on a scale, but i'd be surprised if it weighed less than 10.5 lbs. So i suppose it's possible to cut corners and make a lightweight 5-string, but it seems like when you add that extra string, you're gonna hafta beef the rest of the instrument up to support it.