I've programmed an app that will go through all the character files and rewrite them with just the username, password, and blank stats. Total estimated down time: 5 minutes. It takes longer to load the file names (~10 seconds for 500 characters) than it does to clear them (~2 seconds).
If I have time, it might even be able to fix characters that are currently "chopped" or in other ways "broken". ...which gives me a great idea for an automated character repair that could run say twice a day every day. Once at noon and once at midnight. Hmm, beta team get ready.