Ad,
You never did say where you were planning to be backpacking. Whatever you take for equipment, whether knives or anything else, really ought to be determined by what you're going to be doing with it.
Most of the backpacking that I have ever done falls under the category of "low impact." In most places and circumstances, I strongly agree with the philosphy of "leave nothing but (a few!) footprints and take nothing but pictures." Under those conditions, a khukuri is strictly emergency equipment. It's true that emergency equipment must be able to do the job when needed, but in general, you don't need and shouldn't expect to carry the "perfect" tool for each possible emergency task. As long as you can accomplish what you can reasonably expect to need, your emergency tools should be selected for carryability rather than the satisfaction of having a stout knife in your hand. If your chopping efficiency is reduced because you don't have a super chopping khukuri, that is not normally going to be a problem. You shouldn't be chopping anyway unless it's an emergency and then you won't be chopping much.
IOW, I'd recommend carrying a moderate sized knife on a backpacking trip and leaving the khukuri home where you'll be doing your chopping.
If you're going someplace where you will be camping in "primitive" conditions and there is no concern for leaving the place as you found it, then have at it, but I don't see that there are very many such places. National parks, national forests, designated wilderness areas and such are almost certainly not such places. The folks who trek in there following you will not thank you for hacking up the vegetation unless you are the designated trail-maintenance crew.
Paul