[Dovecot] Compressing existing maildirs

I've just enabled zlib for our users, and am looking at how to compress the existing files. The routine for doing this at http://wiki2.dovecot.org/Plugins/Zlib seems a bit complicated. What do you think about simply doing:

find /var/vmail -type f -name "*,S=*" -mtime +1 -exec gzip -S Z -6 '{}' +

I.e. find all maildir-files:

- with size in the name ("*,S=*")
- modified before I enabled zlib plugin
- compress them 
- add the Z suffix
- keep timestamps (gzip does that by default)

It's of course racy without the maildirlock, but are there any other problems with this approach ?

-jf