A couple of things I noticed: When they are laying up the composite walls, there are only four or five upright aluminum studs in the whole wall, the floor looks like a composite, also. They must be getting a lot of stiffness in the wall structure from the Azdel, the fiberglass, and foam. They interlock the walls to floor and walls to roof with an aluminum channel, it looked like those were fastened with self-tapping screws. That's probably a pretty good way of attachment.
They really tout the "Lite-ply" like it's some sort of advanced material. Really, it's the use of Alder instead of Fir that makes the weight difference. As for CNC machining, I know some home hobbyists that have three axis machines, now. Nothing special there.
Overall, IMO, they're building a product that is about mainstream or maybe a touch better in some respects. The glowing endorsements from the crew was a bit much but to be expected.