it is not a fair test because you may get confused by the starter itself as well as the different the texture and feel in the mouth.
However, it is indeed a comparative test on taste. The thing is that if you use cold fermentation, the 2 flour will develop in a different way, and therefore it is not the flour being better then the other, but will be you that did not have "extracted the proper flavour out of it.
Scientifically there are many reasons that make a flour better then another, but trust me I would not take a firm decision on a type of flour lightly. I have tested many flours, both in a professional environment and home setting, for pizza and bread, with commercial yeast and starters (wild yeast),then I got to my conclusion.
It is also interesting to note, that none of the major pizzerias in Naples uses San Felice, even though it is produced at the outskirt of the city. If not using Caputo, they rather use a flour from Lazio or the Figna from further north.