Applying ED to UChicago is highly beneficial. I can say this for certain as I am an incoming first year who was deferred EA and then admitted ED2. Here is the reasoning:
Top schools like UChi put lots of time and consideration into each admitted student’s application to determine that they are a good fit for the school. They want to have a higher yield rate, meaning more students that they admit commit to attending. Applying ED at UChicago tells the admissions committee that it’s your top choice–something they hold especially important because of the obsession that many kids have with the Ivy League. Chicago is a quirky school and if you know you want to go there and you are in either an affluent financial position or one that guarantees full aid, you should 100% apply to UChicago ED. If you’re not so sure, you should apply EA instead of RD, but keep in mind that Chicago knows they aren’t your first priority (barring financial limitations, but I’m afraid the world isn’t that generous as of yet) and thus they’ll be more inclined to take ED admits unless you can really stand out among the EA group, who I can almost guarantee are applying to many other top 20 schools. Good luck with the app process.