I've got a WartHog that I've had for at least 10 years. Works great especially on kitchen knives is idiot & goof proof. No setting up & maintaining proper angles. I like it. (I see they've changed the design some though)
I've had one of these for around 8 years. They are awesome. My hunt club buddies used to make me bring it to deer camp and would line up wanting to use it.