Hmm...certainly an interesting idea. It'll be neat to see how this concept pans out.
- Better visibility from the cockpit
- Less risk of losing your stuff
- Drier for your stuff
- Nice clean aesthetic
- Lower center of gravity
- Solution for areas requiring multi-chamber boats
- Additional failure point (ie. "constant vigilance...is important")
- Raft deflates every time you access this area.
- Center of gravity is moved back.
- The dual long/skinny drybags look difficult to utilize for backpacking.
- The drybags are supposed to be filled with gear after they are in the boat, so packing/unpacking could be more time consuming.
The weight shift (lower but further back) is interesting. Alpacka says it's great and I'm sure the lower center of gravity is awesome, but I wonder if there is also a degradation by losing the weight up at the bow. The boat seems more stern heavy like this, but I'm not experienced enough to weigh in on the overall effect. It'll be interesting to see some thoughts from actual users.
Regarding the weight (20oz), I suspect most of it is in the dry bags. I wonder if these could be omitted and gear could be tossed into the boat in a few silnylon sacks (which would shift around a bit). That's more appealing to me and would cost half as much. As is, the additional dry sacks look like a lot (~1 lbs) of dead weight when hiking, unless someone comes out with a pack that utilizes these well. Also, it doesn't appear that a framed backpack would fit in the boat, so strapping a pack to the bow would still be necessary unless you're going with a frameless pack.
Overall, it looks like a nice setup for boating-centric trips where you're not regularly backpacking. For trips with a significant hiking component, the added weight and hassle of transitioning gear (between these chambers and a pack that would still strapped to the bow) seems like more hassle than it's worth. With that said, you can always leave the additional dry sacks at home and just use the boat normally with just the 2-3oz for the zipper coming along.