I'm not trying to be the contrarian here but the baking steel has not blown me away. I recently bought the new 3/8th inch "Modernist Cuisine" model, and although it does a nice job, it hasn't been earth changing on the difference in my pies. Perhaps my stone was a very high quality one, it came from Williams-Sonoma, but I have only reduced the bake time of my NY style by about a minute, and it comes with the very real risk of the bottom of the pie burning.
Dave, contrary to what you might read on Slice, steel is not a one size fits all solution. It is only suitable for very particular oven owners with very particular goals. For these people, steel is a godsend, but, for anyone else, steel, at best, is unnecessary, and, at worse, counterproductive.
First off, you have to have a preference for 4 minute NY style pizza. It's puffy, but generally not that crispy. Very few people have tasted 4 minute pies, and, generally speaking, most love them when they try them, but, with some people, the conditioning towards golden brown and crispy is so strong, that 4 minutes doesn't thrill them. For this group, steel is a complete waste of time.
Secondly, if your oven doesn't have a broiler in the main compartment do not buy steel. Steel is a bottom browning accelerator. The only way of matching the faster rate of bottom browning is by using the broiler at the same time (and positioning the stone close to the broiler so the broiler has plenty of impact).
Third, your oven MUST hit 550 for that mystical 4 minute bake. Mark (Communist) does his magic at 530, but, I think, just to be safe, 550 is about as low as you want to go. Kenji's 4 minute bakes at 450 have absolutely no correlation to the results members have seen on this forum. I think his non traditional formula might be part of the outlier equation, but there has to be more than that. I definitely don't think he's stretching the truth or misrepresenting his equipment/results (he thought I was), but the bottom line is that his results are quite possibly the worst barometer for judging the effectiveness of steel at lower temps and lighter gauges.
Fourth, steel is only as good as the thickness you buy. Unless one has an oven that can hit 600 (1 in 50 maybe?), 1/4" steel is garbage (and no better than less expensive cordierite). 3/8" is really cutting it close. I've never recommended either thickness. 1/2" can be heavy, but if you cut it in half, it's far more manageable (thanks JD!).
Kenji has done the beginning pizzamaking community a tremendous disservice by implying that steel is for everyone. It's not. It's miraculous for some, but not for all.