Magnet,
Do you have wrist problems? I sometimes get wrist pain. It really started when I began fishing in Alaska... big rods, big flies and way too many big fish. Of course age and the repetitive motion of casting has taken its toll. I also found my wrist would hurt/ tire when I started fishing longer rods. So I made some adjustments. Part of the fatigue came from the feeling that I was holding up the tip of the rod during the drift. Easy solution...I matched the rod with a better reel. Also, I changed my casting stroke. The increased leverage of the longer rods did not match well with my "wristy" style. Now I derive power more from my shoulder and elbow. I hope to be casting for a long time.
Anyway, I am not sure you need a fighting butt to solve wrist fatigue. To me a fighting but adds unnecessary weight and may add to shoulder fatigue while extending my arm during the drift phase. It may just be in my head of course. Now if you are fighting monster trout all day that is another story.
On a final note, I also hope the Echos are available soon. I know they are worth the wait.