I bought one of these "uncappers" late last year. Very pleasant customer service. I harvested several hundred pounds of honey from last year's crop, and all my spring honey this year, using the uncapper. I have not noticed any pitting in the blades, or a change in honey flavor. Most frames go through smoothly. Harder combs take a couple of slow angled passes, giving the blades (which are not really sharp at all) time to cut down into the cells. Low places on the frame need to be hit with an uncapping fork or roller punch. I have used it successfully with Deep plastic foundation and wax foundation frames. I also used it successfully with older medium foundationless frames.
Overall, I am pleased with the product. It gives me an alternative that saves a little bit of time, doesn't leave me a pile of wax to deal with when I don't want to, and helps me avoid hot knives. It's simple to use, and works as advertised.
Two cautions...1) Don't go too fast. If you push the comb too fast through the process, it will not cut deep enough on harder wax, and you could crush more than slice. 2) If you see any buildup of wax on the roller, keep a plastic comb nearby to clean the blades between frames. Wax can sometimes stick to the roller. When it comes around and mashes into the comb again, it can crush in and then pull comb off of the foundation (as seen in the advertisement video). This is not a problem as long as you are taking care and not rushing like a mad man to make it look like the best thing in the world!!!