I always loved the cleverness of that one. Only change I would have made is to invert the rudder so it would both double as a mount for the rear foils and generate proverse roll when using it for turns in the air.
Lots of people have experimented with mounted hydrofoils under seaplanes, but got poor results. Part of the problem is that waves radically change how much lift hydrofoils generate. The other problem is that hydrofoils are vulnerable to flotsam.
There was a guy in France who built an RC model in the late 1980s, and the airplane had the same issues of complicated transition to flight that the original full size had. It looked beuatiful, the design was pretty nice.