[davexunit]

>There's a huge difference in practical complexity than the theoretical one.

This resonates with me. I write a lot of Scheme, and often enough someone comes along saying that association lists (simple lists of pairs) are terrible because lookup time is linear and that I should be using hash tables. However, they don't realize that hash tables are only faster when the mapping is very large and come with a penalty of no longer having a persistent data structure.