I think that the lighter thinner bladed khuks are for more machete stuff.
I think the heavier bladed ones are for more heavy chopping.
For me, I think that there's like kind of a line between how heavy something is, what kind of edge something has, and the overall shape of the blade and the handle that make it a good all around khukuri for me.
I think you can buy the model that looks like it might work for you, but you really can't tell if it will till you get it.
For instance some khuk handles seem to really swell right behind the bolster. This type of handle really gives my hand cramps.
Some khukuris are too heavy. You'd think a heavier khuk would be a better chopper but for me not always. I find I can chop thru an 8" tree better with a khuk that is pound and a half or less a lot quicker than with a 2 pounder cause the heavier khuk wears you out quicker.
Another thing is the edge angle. A khukuri with a fat steep edge more like an axe will not penetrate as far into the wood, and will require more chops to get the same amount of wood out. It also jars your hand more cause there is more resistance. The edge may be more durable, some say, but I like the thinner sharper edge. It's like the difference between a Boy Scout Axe and a Granfors Bruks. Also the steeper angle is more difficult to machete with.
A lot of people like the really long khuks but these don't really work for me. I think something 16 to 18" is better for me. Much longer and the blade kind of gets in the way. 16 and 17 is ideal.
Another of the things I like a khuk for is with the curve of the blade you can come up to a log blocking the trail, kind of lean over and actually cut underneath the log as long as you have maybe 6 or 8" of space. This is harder to do with the longer blades, and impossible with an axe. With the khuk you can kind of be like a beaver and remove wood all way round what you are cutting with out having to change position over and over. This is one of the great beauties of them for me.
So the ideal one for me is something around a pound and a half, with a thinner handle, and a thinner edge with a fine edge. You can carry it in the woods without tightening your belt a notch, you can chop most stuff with it without much fatigue, you can swing it like a machete too.
That is the beauty of them. They chop as well as most hatchets and are suitable for machete work. You can use them like a draw knife. Just a fantastic all around thing.