Norma, I specifically recall that, when you worked with soapstone, you were getting bake times that weren't much better than your normal cordierite stone. It was a highly disappointing experience, both for you, as the person making the pizza and expecting superior results, and for me, being the one that recommended soapstone. I remember you posting photos of your stones, and the stones looking right, but the baking properties weren't up to snuff. Your experiences, along with Dave's (Tampa) were the turning point for me in my decision to stop recommending soapstone, because the composition could vary too much from stone to stone, giving the buyer no guarantee of good conductivity.
Even if your soapstone is exactly the same as mine, it wouldn't have the conductivity of steel. My oven runs 25 degrees hotter, so I'm able to pre-heat it to 525 and end up with a 550 degree stone that gives me 4 minute bakes. At 525, though, it would be pretty anemic.