After long delays, I updated from 2.8.6 to 3.2.1.
After updating (which I have since rolled-back) various characters are displayed incorrectly. Apostrophes and hyphens are displayed as a diamond with a question mark inside (see URL below for a screen grab of the 3.2.1 version).
There was a MySQL 4.x to 5.x migration, but via phpmyadmin I can browse to the same rows for the most recent posts and see that the data are plain apostrophes and hyphens. Thus I doubt I have a MySQL migration issue (database was dumped using mysqldump and both with/without --default-character-set=utf8, imported into a new 5.0 database using phpmyadmin, same results).