Thanks Matt, please could you post a photo of you seatDave,
Your insight and experience is good. I understand the need to flex the body when you paddle. As with many things this is a balance of personal desires for the best situation, and for a given person.
In my mind to break it down, Meade's seat is a great sailing and lounging seat. Horton's and Axel's are good paddling and sailing seats, and somewhat OK lounging seats. LFH tried to come up with a seat that held your upper backbody and also allowed the shoulders to flex independently. It does this I can attest to, I love the flex I get from my version of his seat. I will note I don't see many modern versions of his seat plan in action. The core of his design, ,as I can tell, is the pivot bar is is low enough to allow the upper back to expand beyond it, to not get trapped down low. Most larger modern seats I see do not have this flex in them. Where I ended, with my version of his seat, is the lower piece of plywood, that gives the seat its sheer strength, also supports my lower back very well. I then have the back rest available for lounging and full press support, which is also independently actuated.
But please understand this is very much a work in progress, I am testing here and not professing at all and open to input.
Also, I get what you mean by the good low paddling support some of the better modern seats give, along with full body flex. But one of my issues with them is that there is no lounging position available for the paddler. This is a position I appreciate, I really like being able to layback. And I would think any codger who is out paddling might enjoy also. I am not out to do lots of miles, but am enjoying myself.