The 2004/5 Khyber is a pretty black board with an interesting looking carnivorous fish graphic. Perhaps the logo is a reference to the board's inspiration, the Burton Fish.
As it happens the Khyber is similar in plan shape to Burton's Malolo ("Flying Fish"), which is touted as a sort of detuned/ less extreme/ compromise Fish board. Putting the two boards side by side shows that the Burton's nose has slightly more lift to it, and the Burton's camber is greater. A quick flex of the boards shows that the Khyber is stiffer, probably accounting for the reduced camber.
To ride the Khyber I set my hard bindings the same way I usually do for powder: 50 degree parallel. As the Khyber doesn't have a reference stance marked in the 4x4 (when will Burton move to this?) I stuck the bindings in the closest set of holes. That gave a reasonable alpine stance centered as marked. I doubt the holes are in fact centered: most likely they're set back as the tail of the board is comparitively quite short.
I rode the Khyber 160 in deep powder after a week or so's riding of the same on a Fish 156HD (the stiff one). The boards were set-up identically.
The day I used the Khyber we rode mostly open glaciated terrain. This isn't challenging to ride, although the views can be spectacular. This day we had a slight crust about 20cm down in the powder just to keep things interesting. This is the sort of stuff which you can feel and just about hear when you're cranked over in the turn. It's waiting there for you to bury the board's nose, after which you'll be lucky not to break an ankle.
The board rode the way you'd expect it to do: part way between a Fish and a more traditional powder board like a large Burton Canyon.
In open terrain the board accelerated noticeably more quickly than the Fish. My boards were prepared with the correct temperature wax each day, so the Khyber's increased size presumably accounts for this feeling.
Once you're running, the ride on the Khyber was pretty similar to any large powder board. That's significant - I found this to feel like a traditional board with a stiff tail. More like a Solomon Fastback than like the Fish. It may have been the conditions on the day. The nasty little buried layer was snatching at the board occasionally, threatening to auger the whole system into the glacier. Hence I favored the back half of the board (which you can see in the shots from the day). To do this a softer tail (or a smaller one like the Fish) would I think have been more helpful.
I didn't get chance to try the Khyber in "proper" trees, although I thrashed it around a few little ones here and there for good measure. Impressions here were as above - in the trees it's all about how the tail works, and this one works the way it looks. For me I'd take a smaller tail like the Fish, or probably a softer more traditional tail - I don't think that for my weight and [aggressive] style that this is the right compromise. That doesn't mean to say it won't be perfect for many people in many circumstances.
It's an interesting board and worth a ride, but I think I'll stick with my Fish.
Update
For 2005-2006 Prior detuned the Khyber considerably. The new model's still tapered, but the pin-tail is much less pronounced. The rationale as explained to me involved the long ride-out from the Khyber run in Whistler, but I reckon it's more likely that Burton got a little upset at quite how closely the original Khyber described here matched their Malolo.
The 2007 Malolo is pictured right.. It rides rather differently from the 2004-5 Khyber and is well worth a ride.