Cash,
I have personally never owned one of these blades or kits because the style is "too late" for any historical impression I've ever done. However, I had a buddy who owned one and he could sharpen a blade and said it sharpened well. However, because of its size, he never actually used it that much so even he could not answer a question on how well the edge would hold up.
I've made a few of the other style Solingen blades readily available from the market into knives over the years, though. I used a four inch Solingen blade and hafted it with a decent size spike from my Dad's spike buck, then made a scabbard and presented it to him. Since at our hunt club, many of us helped skin and butcher deer we or other club members shot, we got some good idea on how long an edge would last. I asked Dad a couple years later how he liked the knife and he related it did not hold an edge well. After I asked him to look at it, THAT'S when I found out after four decades that Dad didn't really know how to sharpen a knife and it was as dull as it could be. So I sharpened it and used it.
Normally two of us worked on skinning a deer at a time at our club. I found that by the time we got to the second or third deer, that the edge needed "touching up." So I would rate that blade as "good" but not great. However, it did not cost what a "great" blade cost then. I'm also not sure how it would have compared to an original and common blade like an original trade knife, though I suspect it is as good quality as most of those original trade knife blades were.
Gus