Since its the warp doing most of the work, I wouldn’t be able to sleep without knowing there was at least some chain on my main anchor, however these look like they could be handy for lunch stops or as a stern anchor in certain situations etc. They have obviously been around for quite a while, yet I don’t know of any chandlers here (in Australia) that sell them, only available straight from the manufacturer or sometimes on eBay I think.
Regrettably, they are no longer available as new here in the USA. I have used a small one for years as a kedging and safety anchor and they do work as advertised. I would not use it as a “primary” as it would need chain for that. The use of a kellet helps, but I think the best use of one is for kedging off, or a “lunch” hook when it’s holding can be constantly watched.
I know someone who has 30 of them for sale, let me know if your interested