Eric has a great point. I’m sure tsugaru shamisen wouldn’t have been made if similar discussion didn’t happen back then. No doubt, this is a controversial topic, especially for those who are locked into the current paradigm (most of those people probably aren’t excited about gaijin playing shamisen anyway
). This is why I stress that these future models are not meant to replace the current shamisen, but to stand along side it, as an additional way to unlock the most potential of the player. After all, there is an incredible variety of guitars out there. Why not shamisen? 
Karl:
Actually, Masahiro’s dou is supersized.
The estimate size for beginner tsugaru shamisen are 四部大 (Size four), standard tsugaru is 五部大 (Size 5). Masahiro’s shamisen is 七部大 (Size seven)! Only maybe 2 centimeters larger, but that adds up and does affect the wrist.
But I digress. Rounding the bottom of the dou, good idea! Do you mean the same roundness as a banjo, or still having a squareness to it?
Just had a thought. What about having a broad, hooked attachment (probably made out of plastic) that connects to the bottom of the dou, and acts as a stabilizer when rested on the leg?
Having a thin necked shamisen would be a cool model to have. When we get into the designing stage, we can think of ways to make it work in reality. Perhaps a truss rod?
Man, this would be such an awesome thing to have a conference about.
(四味線)
You mention the cost, and I think that may be why it looks the way it does today. I don’t think there have been many tests with changing the body into weird shapes as skinning would be more troublesome. Changing the body into a way that still allows for easy skinning could achieve an even better sound, but we don’t know that. I agree that the cost vs. benefit might be discouraging in this case. I can hold the shamisen with one arm today, but I don’t feel that I can move my right arm freely while doing it, and that is what I want to improve.
Got a surprised LOL from me.