Only my two cents, but I have cleared over the last six years about 10 acres by hand using machetes, choppers, chain saws, clippers and brushcutter. The vegetation is mixed: cane reed, bamboo, pine, willd pear thornbrush, wild vine, wild olive, wild rose, cedar and various "cuss you cuss you cuss you" vegetation. The earth is hard, stony, shale and clay, mud in winter and hard concrete in summer.
The machete should be light, and balanced for fast chopping. The blade is therefore thin, and exactly as soapboxpreacher says, it should not be one dimensional. That is a great term for the feel of the blades. A chopper comes down in one line, and hits solid in the same line as the angle of attack. Its weight and momentum stability give it such good penetration and chopping power. The machetes flexibility allows it to be twisted mid flight, like a good sword, and the angle of attack shifts slighty on impact if the cutting stroke is not achieved, which allows for a splitting and ripping effect.
The trick is the flexibility of the machete, due to its thin blade, and not about length. In fact, I find the 24" Latin Machete too long to be properly called machete.
https://picasaweb.google.com/104450...hkey=Gv1sRgCNvIheH14b2aJQ#5633908756381681906
https://picasaweb.google.com/104450...hkey=Gv1sRgCNvIheH14b2aJQ#5633908578996800434
The length of it, on the power stroke, creates a mass momentum, which severely limits hand flexibility. I use it only for bloodcutting thornbush, just to keep away from it, and as a light masochistic axe, for chipping and weakening roots, digging into the top soil. The long machete becomes a bad chopper, albeit one specialized for nasty bramble
So length can be a limitation for a machete, although it all depends on its width, hardness, and the hands of the user. In practice, I have found the ideal machete length to be ithe 15-16 inch length with a blade thickness of tenth of an inch. This lets me work quickly and fast cutting plantlife with FOLIAGE without tiring and without worrying about clearing space for the chop. Whereas a chopper of the exact same length would also be on my belt, in a flat bevel grind, quarter inch thick, and be a better cutting device for thickweed, young trees, and the like, and also for prying tasks. Clearing land first pass with just these two devices allows you to come back later with power tools for clearing to soil.
One dimensionality vs three dimensionality. A great machere dances in the hand like a small well balanced stiletto. Why are they so cheap? I don't know for sure, but I would guess, because making such a blade in this size is much easier than making a good solid chopper (unless it is an axe), and also probably for the sheer production volume.
Sorry to run long, but the quest for the best machete fascinates me. Can't wait for my woodsmans pal.