The one remaining doubt I have about a GP paddle is, does it require an exaggerated twist and lean to take full advantage of the blade length? It seems to me that without such an effort, only a portion of the blade would be doing any work. This might be great exercise and force torso rotation, but it could be very tiring.

Also, it's obvious that I am totally ignorant about GP technique, but what do you mean that paddle width should be based on what is comfortable to grip. Most of the GP paddles that I have seen, had very narrow blades. I didn't actually measure them, but 2 1/2" was my guess.

I was able to install drip rings on the Euro paddles that I built and if I build the GP the same way, that wouldn't be a problem. My plan would be to shape the handle, or shaft section first, install the drip rings and then glue the blade pieces on both sides of the shaft to get the blade width. I would also use a router to hollow the shaft and then glue a cover piece on the handle to cover the trough. I used maple on my Euro paddles, using a similar method to produce a hollow shaft. They turned out to be very strong and extremely light.

The main problem with the Euro design is that fiberglassing was necessary to keep the whole thing together and that increased the weight to the degree that it isn't worth the trouble.