Looking at the picture in the ad, I had several thoughts in response.
I asked myself, why didn't they just make it a design that could take off from water too? Yes, it is sitting low in the water -- but that seems to give it greater stability in the water compared to a flying boat or conventional floatplane. Then I thought about how it was intended to be used, as a scout plane from a warship. Such planes, in use by many navies at the time, were launched from the ship, landed on water near the ship, and retrieved by a crane. In normal operation, they would not take off from water. There might be few instances when they would need to. One we know of is when one of the Colorado search planes landed in a lagoon to ask questions, then took off again to continue searching. That might be one of few times they ever took off from water (wondering how much training they even had in doing so). If the engineers designing this plane thought it would never need to take off from water, then this design makes sense (which it didn't to me before).
A prop plane designed for a water takeoff needs to have the engine high enough above the water that the propeller clears. That means either raising the entire plane high up on floats, or placing the engine or engines high up on the airplane. Either would be detrimental to stability and aerodynamic efficiency. This design lets the plane have a more conventional landplane shape with the benefits to performance and range that provides (and have no drag from fixed landing gear), yet still land on water and be recovered by crane. They forgo being able to take off from water but they may have reasoned that in normal operations it would never need to.
The choice of a W-configuration engine makes sense based on the picture, because the bottom of the engine isn't in the water as it would be with a radial, yet it allows for a powerful, multi-cylindered engine that is still relatively compact.
I also thought, were they hoping to sell more of these based on a successful ocean crossing that would demonstrate its superior range? Navies might care a lot about greater range for their scoutplanes.
LTM,
Don