Dayenu has fifteen verses, supposedly to represent the fifteen steps leading to the inner court of the Second Temple - the landing place of the 15th stanza of Dayenu.  The first five verses deliver us from slavery, the next five bring miracles and wonders, and the last five deal with our closeness to HaShem, or our delivery to a moral and ethical life of Torah.  Rather than asking if "it would have been enough," going fifteen rounds with Dayenu makes us examine life as free people.

During Iranian and Afghani seders, people hit each other with green onions during the 9th verse of Dayenu when we proclaim that the manna from heaven would have been good enough. Why? It's a reminder of being a slave in Egypt, at the far end of a lashing.  Another interpretation is that it's a reference from Numbers 11:5-6, where the Israelites long for the onions they had in Egypt. The onion-slinging is a modern day repentence for their whining in the desert. However dismayed they were with the daily manna it was preferable to slavery. And finally, it eliminates hierarchy - kids hit parents, parents hit grandparents, cousins hit cousins, and it continues until someone gets an onion in the eye.

Los Angeleno-Iranian Jew Sam Yebri writes "One Passover, I even attacked the back of my mother's head because she had refused to buy me any video games that year. I was 17." 

haggadah Section: -- Cup #2 & Dayenu
Source: Breslov Haggadah, Sam Yebri, The Geulah Papyrus,