Ok, after popular demand, I have removed the cron approach to updating the www directories for the projects. /project/<project-name>/public_html is now being symlinked to from /var/www/project/<project-name> so any changes you make will be instant.
I'm thinking about doing the same with FTP but that would mean I couldn't do the chroot anymore (unless I'm missing something) and I'm not sure we want to do that yet.
Erik.