The move was triggered when I started to have real problems consulting the boxes remotely over IMAP (I use dovecot). The folders started to get messed up and the system was slow.
I always knew that maildir have clear advantages for my scenario, but I thought that I would have a hard time migrating my services and scripts. I was surprised how easy it was when I really got my hands dirty!
First, used a great Perl script mb2md to convert my existing mailboxes. Then changed some lines on my Postfix configuration. Since I do my mail processing with the Perl module Email::Filter, it was just a mater of changing the paths, and it worked magically!
Never thought it was so easy…. Oh, and dovecot now behaves correctly :-)
Goodbye mbox, you served me well…