On top of everything said here, HI offers a lifetime warranty on all khuks to the original owner of the khuk...not this 5 years business that cold steel offers.
HI khuks are made from 1095 truck springs. The kamis (bladesmith) try to harvest Mercedes truck springs if at all possible. Each khuk is hand forged, fitted, and finished. If you want the "real deal", you need to get an HI.
I've owned a couple of Cold Steel's KLO's (Khuk-like objects

). They aren't bad at all, really. But they are just a khukuri shaped knife. I've never had one fail on me, but I've never wrenched on a CS KLO like I have my khuks from HI.
As far as handle material goes, it's all personal preference. Horn tends to look a little silky or glossy, but is sometimes slick (easily fixed with some sand paper). Wood is much more "mod-able" where you can sand, stain, and seal it to your liking. As far as hidden or exposed/slab (called Chiruwa by HI) tang, either one is fine. You'd have to be a gorilla to break either other them. I have both, and like both just about equally as well.
If you have any specific questions about HI khuks, the different models, or want more first hand experience, stop by the HI forum and ask a question or two
