Pound for pound a most khukuris will not chop as well as a hatchet, so mostly when I am backpacking I take a hatchet because I get more chop per weight.
However if you are trail clearing, chopping a variety of diameter vegetation, then a khukuri is the way to go, because it can machete or it can chop.
Myself I prefer in the 15 to 18" model and pound to pound and a half. Go above that weight and I feel you cannot swing it fast enough to cut the small stuff. Go below about 1 lb 4oz(for me) and it loses too much of it's chopping ability.
Also many khukuris have too steep of an edge. This may keep it from binding when you are chopping but greatly cuts down on the efficiency of each chop, and also with the steep edge you wind up beating the smaller limbs off instead of slicing them.
Most of the khukuri makers make decent blades but I think for best use the criteria above should be met.