I use my food processor only for myself but I got used to the added capacity of the 14-cup Cuiinart, not only for making pizza dough but for other applications. Also, at the time I purchased it, price was not a particular concern.
The main advantage of the larger capacity unit is the ability to make more dough, whether it is for conducting multiple experiments, freezing for future use, or whatever. You might want to solicit the views and opinions of our members who have the 12-cup food processors.
In my case, I would have rather spent the added money to get the larger unit than to get a smaller unit that was inadequate and thereafter regret not having purchased the larger unit. In general, it seems to me that people who buy the smaller size of anything are more likely to regret not having gone larger than the other way around. People find ways and occasions to use the added capacity.