San Marzano is such a wank! Let me tell you this from a food importer who imports both San Marzano and equivalent normal pomodoro pelati.
If I can pass some advice on.
1. Always use Pomodori Pelati. Using chopped tomatoes is just asking for trouble as they are never of equal quality.
2. In an ideal world, the idea of San Marzano tomatoes is fantastic and quality is chalk and cheese. However, the grand majority of the products nowadays offer no added qualities because its such an over farmed market.
Having said that, I am using De Cecco Peeled San Marzano tomatoes tonight purely for Wank value
Save your money and buy a quality brand of italian peeled.