I believe I can help out... I'm a noob on this site, but this is something I know a lot about. I figured I'd lend you nice guys a hand since I'm learning so much about dough fermentation :-)
-San Marzano is a REGION--nothing more.
-Same as Champagne is a region where they grow grapes for champagne. Grapes made in a similar fashion NOT in the Champagne province of France is called Sparkling White Wine.
-Same as Tequila is a region. Tequila made from agave NOT near the city of Tequila in Mexico is not technially tequila.
The words, San Marzano, on the can mean JACK SH!T. The only way to tell what you've got is the official stamp on the back of the can. That STAMP costs a lot of money! That's why you pay $5/can for "official" SM tomatoes. However, some bona fide SM Tomato distributors don't get the stamp on theirs because it's stupid.
Some places are BASED and even PACKAGE the tomatoes in Naples even though they didn't grow them there. ("There" meaning on the hillside of Mount Vesuvius). The tomatoes might have been grown in Scandinavia for all we know!
They do that with all sorts of stuff... like olive oil. People go through all the trouble to say it's ITALIAN olive oil. Who cares. Fun fact: actually SPAIN makes the best olive oil, period. Try it some time. I mean "try" as in compare the olive oils STRAIGHT. Sip them.
I digress.. Use whatever tomatoes taste good. SM Tomatoes are nothing more than a plum tomato. They have less seeds and are naturally sweeter which makes them ideal for pizza. You don't have to add sugar or wine to the recipe. If you're using a cheap knock off that TASTES GOOD. Then do that.
NOTE: The ONLY REASON you should specifically use San Marzano tomatoes is if you're trying to stay true to the real Neapolitan pizza as laid out by the Italian Ministry of Agriculture:
- 35 cm in diameter
- 0.3 cm thickness
- 1.5 cm crust thickness
- fresh mozzarella
- San Marzano tomatoes from Mt. Vesuvius
- cooked at 485 degrees celcius in a wood fired oven
Another fun fact: It will be impossible to recreate a real Napoletana pizza because they just use what's FRESH in their area. In fact, most italian cooks, period, use indigenous ingredients.
Most people on this website are looking for "New York" pizza anyways. If you're using pre-shredded or a block of mozzarella, you're way out of your league here. Save your money; just use whatever can of tomatoes you like the taste of, can get CONSISTENTLY (most importantly), and modify the recipe as needed.
Hope this helps!