I've built quite a few with lattice bracing of 6K Carbon Fibre Tow / Balsa / 6K Carbon Fibre Tow. The tops are 0.8 to 0.9 mm thick.
Volume is about as loud as any ukulele I've heard. Very punchy, great sustain. It's a different sound to a conventional braced instrument. People that buy them use them more as an instrument to cut through a mix of others. Much like a banjo or mandolin does.