I haven't been around much, but I wanted to add a couple of cents.....
...I'm missing some fingers on my right hand, so gripping things sometimes becomes fatiguing very quickly.
Might I suggest a review of your technique? I'm pretty sure that you already have it down to a science, as this is clearly "not your first rodeo", but I think that lots of people try to take too big of a "bite" when using carving axes/hatchets.
To remove a lot of material, do you cut a series of notches, working up towards yourself, then take one longer swipe at it to remove the bulk of what you just loosened? When you drop the blade into the material, do you twist the blade after it has cut a notch, to help loosen the material?
Might be worth describing how all of you use the hatchets? I know I saw a good reference on-line somewhere, but I can't find it. It was related to Swedish Carving techniques...using an axe.
Cheers,
J