EBarnacle (before):"One of the major reasons I sold the Edeophone was its weight. At that time, I was constantly on stage with a group which generally played standing up. The Edeophone was too much for my wrists, even then. As a fencer, my wrists are not exactly weak but the constant load was too much for them".
(now: "The instrument was a 56 button tenor treble and it weighed significantly more than my then and current Wheatstone. Even though it was ebony ended and beautiful, it weighed too much."

RE:If you do talk about *carrying effort* and not about *pumping effort* you do have a rational argument here but as you also report that it was your *wrists* that suffered and not the *thumbs* I get a little bit suspicious still.Can you separate that distictly yourself? Other question are in what position you held the instrument and if you had tried conventional "wrist straps"?

(As a comparable example I can play ( rather energetically) my 2500g baritone-treble standing up without any rest for two hours using my modified handles while the same musical activity with the common 1250g treble demands a rest every 5 minutes. This is the common "ergonomic" experience - if static work is limited to about 10% of the maximal muscular power it can go on "for ever" if energy is supplied)