I don't like the Redbird at all. If one was offered to me for free I would politely decline, especially as I have that liberty.
Here is my main complaint. The paddlers positions, where there is the highest concentration of mass, is extremely low volume underwater coupled with a very low sheer line. With this combination, the canoe cannot raise the mass of the paddler over the wave crest, nor is it deep enough to keep the water from coming in over the top.
If you're set on building it, fix the sheer line at the paddlers position. And pay attention to where you position those seats.