I guess my opinion is somewhere in between the rest. My opinion is this is a good safety accessory for a pretty high price.
You can make suitable safety accessories yourself for little cost and some time, or you can purchase them. Your choice. If you decide to purchase, the Grr-ripper is the best I've seen.
I made my own before the Grr-ripper became available, and I am satisfied I am operating safely. If I had to choose today, I'd do the same, thinking my time is hobby time and making my own is worth it because I enjoy doing it.
Others feel their time is more valuably spent on more "productive" work. Which I believe is reasonable point of view as well. Just not for me.