On socioeconomic diversity, this from the NY Times may be useful: https://www.nytimes.com/interactive/2017/05/25/sunday-review/opinion-pell-table.html?_r=0
Amherst is at #7, Midd at #33.
This may also be helpful: https://www.nytimes.com/interactive/2017/01/18/upshot/some-colleges-have-more-students-from-the-top-1-percent-than-the-bottom-60.html
(Midd #9 “more students from the top 1 percent than the bottom 60 percent”)
Amherst is also more racially diverse. https://nces.ed.gov/collegenavigator/?q=amherst&s=all&fv=230959+164465&cp=1&sl=164465+230959
Undergraduates by Race / ethnicity Amherst/Midd
American Indian or Alaska Native 0% 0%
Asian 14% 6%
Black or African American 12% 3%
Hispanic/Latino 13% 9%
Native Hawaiian or other Pacific Islander 0% 0%
White 42% 64%
Two or more races 5% 5%
Race/ethnicity unknown 4% 1%
Non-resident alien 10% 11%