I bought a Stumpblaster 3p24 a couple years ago and put it behind a 37hp/30hp PTO. I grind stumps professionally but wanted an easy way to cleanup when done. (front loader)
This machine was rated at 30-50hp at PTO. My tractor at the time, being at the low end did a sufficient job but I had to get more efficient so I bought a 60/50hp. I also redesigned and made my own wheel. The factory wheels are ok but are poorly made and don't last long. The factory wheels had 2 sets of effective cutting teeth, they ran out both laterally and radially so you weren't actually using all the teeth, and the configuration on the periphery would not allow you to plunge straight down into a root to start a cut. My new wheel address all those problems, has 3 sets of teeth and is made of much better material.
Would I buy a Stumpblaster for home use? Sure. It's a good concept. Don't expect to use it professionally as is, it won't compete with the Vermeers or Carltons. Just my opinion.