To me, if you are in a cold environment and want a good amount of firewood that will burn for a good time, I'd take a saw with an axe over the machete any day of the week. I processed a nights worth of firewood with a machete in New Hampshire in October, and let me tell you it was a real pain in the butt. It took a lot of time and energy.
On the flipside, the machete is fantastic for gathering kindling and processing thin-to-medium girth wood to make say a chair or bench to sit by the fire. It's also has a huge "fun factor."
I also agree with the fellow who prefers an axe over a hatchet despite the added weight. If you're gonna be a bear, be a grizzly.