They work pretty much the same. The Work Sharp are fantastic. I know I wasn't warned when they went through and sharpened all my knives. CeeDub, who I was working with, had them do mine while I went out on break. I cradle my knives a certain way and they put a razor sharp blade on my paring knife. First time I grabbed it, knowing how I had it sharpened before they resharpened it, the blade sunk deep into my thumb like a hot blade through butter. Had cut cleaned and glued and tossed a glove on. Went straight to their booth and told them I wanted one. They told me to hit them up at last show and they'd sell me the demo cheap. I really miss that sharpener.
If I recall the Ken Onion version was adjustable, in relation to the angle of the edge. That intrigued me but for the price the standard model worked so well with my fillet knives that I just never felt the need to upgrade.
I worked for one particular captain for a couple of seasons and on more than one occasion he grabbed one of my knives to cut a fish. I could cut circles around him with every fish except Halibut. He grew up in Cordova, AK, and had guided and commercial fished halibut for a good many years so he had a ton of experience. Down here we just don't get enough Halibut days for even a deckhand to get that sort of repetition, so when it came to Halibut he was was lightning fast. There were a few days he grabbed one of my knives and dove into some halibut and scared the hell out of himself not expecting such a sharp blade. He never cut himself but there were some close calls.
I love the feeling of the cutting into that first fish with a knive that is fresh off the sharpener. So satisfying!