I hope that no one minds if I revive this thread. I have also thought about using Khukuri's as an alternative for the Chinese Butterfly Sword (also known as Double Southern Knives, or the Human Character Knives). Well actually, I've done more than just think.
I am a kung fu instructor, and I am trained in the Shaolin Human Character Knives. (The name refers to the Chinese character for "human"). There are many different styles, and I believe that the one I practice lends itself well to using the Khukuri. Perhaps there are also other styles that work well, but this is the only one that I know.
A while back, I bought a cheap Cold Steel Kukri for about $15. One day, I got the idea to use it instead of the Human Character Knives. So I bought another cheap Kukri, and I did some training.
In my opinion, they work fine. There are obvious considerations, many of which have been mentioned here. There is no guard, and that is probably the most significant point to consider. Also, the Chinese Butterfly Swords have a special L-shaped guard that can be used to lock weapons. So those techniques are not applicable.
But plenty of other techniques are still applicable. As someone mentioned, they may not be ideal for slashing, but they'll do the trick. And there are chopping techniques in my style, so those will work even better. I feel quite comfortable with double Khukri's, and that is solely due to my training with the Shaolin Human Character Knives. I feel that I could use them effectively against several weapons, especially the Chinese spear, which is the weapon that all Chinese weapons were measured against.
I plan on purchasing some HI Khukuri's. When I do I'll try to take a video of the form and share it here. I'll also try to show some of the combat applications.