What's the real benefit of a deluxe porta potty over a standard one?

For a six-hour reunion, the deluxe unit is worth it mostly for the flush, not the mirror. The flush is a foot pump that rinses the bowl with fresh water from a small tank, so guests aren't looking straight down into the holding tank. That alone makes the unit feel cleaner and cuts the smell people notice when they open the door, especially later in the afternoon once the tank has seen some use.

The sink is handy but it doesn't replace a separate handwash station. With food out, people want to wash before eating too, not only after the toilet. A station out in the open lets the next person get into the unit while someone else is still drying off, so the line moves faster.

At our family reunion last summer we did one deluxe unit for the older relatives, standard units beside it, and a handwash station between the toilets and the food tent. Nobody complained. Ask the company to confirm the flush water and soap get filled at delivery, because a deluxe with an empty fresh tank is just a standard unit with extra plastic.