David, The good news is an ultralite or at least moderately light Alembic does exist. My 4 string Omega Series one weighs in at about 9 pounds. Maybe slightly more. By contrast, my 5 string cocobolo weighs in at 13 plus. The specs on the Series I are: Walnut top and back, either mahogany or vermillion semi hollow core. I think it's mahogany, but compared to the core of my 5 string, which I KNOW is mahogany, it is visually lighter in color.
Mica, if you're reading this maybe you can chime in regarding the core wood for 87-4431. I don't have the wood card, and the appraisal letter doesn't identify the core wood.
Peace,
James