Since this is turning into the mother of all wandering threads I figured I'd jump in a day late and a dollar short.
I'm a confirmed machete user. I also live 80% of my life in Central Brazil. Here a hatchet would be dead weight. Not that we don't have things that a hatchet cuts nicely, its just that we have ALOT of stuff that a hatchet cuts very poorly. As soon as you get off trail you are into vines, weeds, thickets of bamboo, head high grasses, etc. The machete is a mode of transportation that the hatchet will never be.
During the 20% of my life that I'm in the eastern woodlands of PA the hatchet makes alot of sense. When I am there I carry... a 12 inch Ontario machete. Why? It's because I spend 80% of my life in Central Brazil and I have grown accustomed to doing everything with a machete.
Small fixed blades are far more useful as knives than the big knives ever will be. Hatchets and machetes are more useful for chopping than the big knives in my experience.
If you really want to make your life easier in the wilderness get a folding pruning saw. There is no romance in a saw and no slick marketing to make you feel like you
are now part of an elite team of true-life action-adventure heroes. Saws cut wood, nice and straight, and don't batter your joints. They are also safer from a "swing and a miss" standpoint and in a real survival situation that could be important. Folding pruning saws are also easier to use right or left handed than any chopper you have to swing. (I'm writing this with a broken right hand, BTW. How good is your chopping whatever once your strong hand is mangled?)
As far as cutting down pack weight, get real. I don't care what you put in your pack if you have to end the list with... "and a ten pound blob of lard." I have to fight to keep that ten pound blob of lard out of my pack. Right now I am 32 pounds under my lifetime-high weight. Thirty-two pounds is alot of gear. If we're going to quibble about grams lets start trimming grams of fat FIRST.
On a global forum like this there is not going to be a single tool or combination that covers all of the climate zones and vegitation types represented here. Wha tis best for you very well could be nearly useless somewhere else.
The big knife has a function that I, down here in the developing world, appreciate. My BK-7 looks really scary on my belt. Trust me, off the beaten track in Brazil it pays to look a little bit dangerous.
If I had to pick the tools I find most useful in the bush here they would be the Tramontina Machete, a Mora of one type or another, and folding saw. My total investment for these three is about $30 and I doubt you will convince me I have to spend more than that. I still carry my BK-7 as it is also my PSK and, here's the kicker... I like it, cause I am just a little bit dangerous

. Mac