HSS [ M42 ] Toolblanks are still used a lot in industries that deal with any of the HRSA's [inconel et al ] They are better than carbide for heavily interrupted cuts on the above materials. I can't comment on the HSS inserts from Warner as I have never used them, the ones I have used [ very rarely ] are by ARNO WERKZEUGE
I don't really think that HSS inserts are any better than carbide [ especially the sharper types ]. The early days of Carbide when the inserts were more or less all NEGATIVE geometry that needed rigid machines with high power are gone. We now have a multitude of sharp POSITIVE geometries to suit the needs. The pic of a box of inserts that I put in another post were very ,very spendy even with a good discount , I think I have only ever used one 2 or 3 times. It was just expensive extravagance [and folly ] on my part . They [ HSS Inserts ] don't do anything that carbide won't do.in the materials ect that most folks use on this forum.