This is just my opinion, but I think a stone would be better on the kettle. My thought is that the steel has to much thermal mass and would be hard to balance out the steel floor temp to your above pie air temp, thus increasing the likelyhood of burning the bottom of your pizza. If I were to try a steel floor, I'd try and not have the fire under the steel floor, and have the heat redirected to a ceiling steel that would reflect the heat back down to heat up the floor steel. Just my thoughts, but could be totally wrong since I've never used a steel floor. A steel in the oven, I think would work well.