Soapstone is about 2X as conductive as a typical cordierite pizza stone, and a low-carbon pizza steel is about 8X as conductive as soapstone.
Though never particularly popular, soapstone was the go-to for people who wanted more charring and quicker bakes than cordierite could deliver in the days before steel. Since steel plates became common, soapstone has largely gone by the wayside.
While it's possible you might like it, if you want more charring and quicker bakes that typical baking stones deliver, I'd go for the steel over the soapstone.
