Another resource that might be helpful is the results threads on CC. Keep in mind though that they are generally skewed towards acceptances.
Brown RD Class of 2019: http://talk.collegeconfidential.com/brown-university/1752948-brown-university-rd-class-of-2019-results.html#latest
Also, section C of the common data sets give useful admissions info (namely 25-75th percentile test scores)
Brown Class of 2019: http://brown.edu/about/administration/institutional-research/sites/brown.edu.about.administration.institutional-research/files/uploads/CDS_2014-2015_0.pdf
Naviance can be useful, but keep in mind that it is generally too small a sample to have any degree of reliability.