With some amusement, in the testing forum I found
http://www.bladeforums.com/forums/showthread.php?s=&threadid=201071
which contains the below quote from the maker of the AK machetes.
"About the fatigue factor for heavy blades compared to thin blades? Well I will admit that a thinner lighter blade isn’t gong to be as apt to cause fatigue as fast as a heavy blade. However one of the problems that has always been a concern and factor when using thinner, lighter blades is the shock transference into the users hands, wrist, arms, and joints. The symptoms are similar to what was at one time known as “tennis elbow.” We call some of these problems "CTS" now, and this leads to the burning in the hands, and forearm from the shock transference. It is fierce for the plastic handled cheaper machetes, and the really thin knives. Personnel that were using these knives in everyday operations were not happy at all. One thing about the heavier blades they do tend to absorb some of the shock from blade impact, and the better handle materials, and designs cause less blisters from hot spots, and/or from the smooth plastic composites. Some of the cheaper machetes that are floating around have wooden handle that are coated with clear “Shellac” that is strictly for show. Just as inferior shovel handles, hammer handles, rake or axe handles are fire-streaked, and Shellacked so are the cheap machete handles. They look pretty, but they will cause severe blistering of the hands with any prolonged usage."
So true. Did it again this morning. Ow!
A summation of the reply from one of our banned former members is; use the thin blades for vines and light stuff and the heavy blade for the harder woods.
Both writers (who are well known) find the shape of the grip to be very important for control and reduction of fatigue. After reviewing the (many) articles surrounding the thread I have decided that in addition to new grips, a reshaping of the Bushwack grip is probably in order.