sfitcs
I've converted some Redmine to DokuWiki - but not an entire wiki.
Redmine uses a slight variation of Textile, so I used Pandoc to convert from Redmine to almost DokuWiki, then (judiciously) used sed to tidy up. Your mileage will vary according to which DokuWiki plugins you want to use and other factors (namespaces etc).
And no, you didn't miss anything that I'm aware of.