Rich, there is a common misconception among the public that pizza stones absorb water from the crust and make for better pizza. The reality is that pizza stones are not that absorptive. Saltillo tiles and Fibrament happen to be absorptive, but that's a bad thing, because their porosity makes them physically and thermally weak. The cordierite that's used in deck ovens has just about zero porosity and, while the firebrick used in wood fired ovens can be a bit roughly textured, it doesn't absorb much water either. Even if these materials did absorb water, the temperatures at which they're pre-heated to wouldn't allow the water to actually remain water long enough to be absorbed.
Any crust that cordierite or firebrick can make, steel can match. It's just a matter of pre-heating the steel to the right temperature to accommodate for it's additional conductivity. A 3 minute firebrick pizza will look just like a 3 minute pizza baked on steel.
One of the biggest contributors to oven spring is heat, so faster bakes should translate into less breadiness, not more. If you were getting bready results, it wasn't the faster bake, but some other aspect of the recipe.
Heston was influential in getting the ball rolling on metal pizza baking materials, but he didn't go quite far enough for the true pizza aficionado. His research assistant, Chris Young, co-author of Modernist Cuisine, took it a step further and started working with steel plate. I'm not absolutely sure that Chris actually goes thick enough with the plate in the book as I haven't read it yet, but, as far as 'celebrity' chefs go, he's pretty much on the cutting edge of steel pizza baking.
The bottom of the pizza cooks entirely from the stored heat in the hearth and the hearth can be pre-heated to the max oven temp on any shelf in the oven. The hearth will pre-heat a bit faster on the bottom shelf, but, for fast bake times, you will need to position it an upper shelf to allow the broiler to have more impact because you will definitely want to use the broiler during the bake.