Upon further reflection and conversing with Gene and my casting buddy Tom, My above findings are, at the very least debatable. The Walker 16'6" and 17'6" have plenty of flex towards the tip of the rod, and I can see definite flex mid way down the graphite, but there is also some noticeable flex at the cork. To me I see the most pronounced curvature in the middle to the tip. I have attached a photo of the 16'6" Walker being cast to illustrate.
The 15'6" Walker feels more like a Powerlite, without the deeper flex I feel with the other two. But here is the thing, the way a rod feels is not always the same as how we describe it. When I hear a description such as "deeper flex", I think of the rod being more flexible near the cork, but in many cases that flex is more in the upper half of the rod.
With the Powerlights, I find that the rod has a really stiff tip which forces the flex into the middle and butt section of the rod. Below is a picture of the Powerlite 16' 7/8 (which is an extreme example) showing this.
Not all who wander are lost.