So I ask again is it really that much better than other Italian 00 or American flours?
It ultimately comes down to a matter of personal taste and personal preference. However, to get the full benefits of using 00 flours, I think one should use a very high temperature oven for which the 00 flours are better adapted. I have used 00 flours in a home oven environment, both alone and combined with other flours, and have gotten good results but it takes a lot of work and modification of dough formulations and preparation/baking protocols to get those results. And those results will not be as good as those using very high temperature ovens.
Based on the fact that the Caputo 00 flours are the most popular among pizza operators in the U.S. who specialize in the Neapolitan style, especially the Caputo 00 Pizzeria flour, I think it is safe to say that the Caputo flours are the best available in the U.S. at this time. The San Felice 00 flour has gained popularity recently, although it still far lags the Caputo flours in its adoption by pizza operators. Also, the San Felice 00 flour comes only in 55-lb. bags and only through foodservice companies or the importer. No doubt other brands of 00 flour can be used, and there are several on the market, but they are very low volume products and not in the same category as the Caputo flours from a quality and performance standpoint. The lesser brands may appeal to some simply because they are less expensive in many cases. But it is very hard to beat the Caputo flours on quality.
It's hard to compare the 00 flours with American flours because they are vastly different flours with different characteristics and specs. To make an authentic Neapolitan pizza, one would use only 00 flours (and a very high temperature oven). It is possible to make a Neapolitan "style" pizza using domestic flours, and there are several dough recipes that call for using domestic flours, but they will be vastly different from those made using 00 flours. In some instances, one might even like the domestic versions better--again, usually as a matter of personal preference. Many people combine the two types of flour, either because of personal taste preferences or because the blends bake up better in certain ovens, even high temperature ones.
I often suggest that members order a small bag or two of the Caputo Pizzeria flour from PennMac and try the flour out to see if they like it and it otherwise meets their needs. That way, they don't end up with a large (55-lb.) bag of flour to use up if they conclude that it doesn't suit their purposes. For those who like the Caputo Pizzeria flour, it will always be a problem getting the larger bag, for the reasons earlier mentioned. For that reason, some of the members purchase the Caputo Extra Blu 00 flour, which is a lower protein 00 flour. There are several retail and a few online sources for that flour.