The ability to have multiple menus with different prices per item/per guest in one system makes it easy to do accounting without having two separate systems or being able to get accurate reports from each of them separately.
It would be nice if you could see what your profit margin was at any point during an event (like how much did we make vs our cost) but I haven't found anything else like this online so far. If anyone has suggestions please feel free! We are using it primarily for inventory control to ensure we don't run out before events start; also helps us keep up-to-date records about who ate what when which gives me peace of mind knowing they're getting fed well :).