hi @mveplus,
I have Nginx working with Roundcube webmail and phpMyAdmin (served as a sub-folders, not as a sub-domain like webmail.example.com), but not Awstats and Cluebringer webui since they require authentication against LDAP/SQL server with basic auth.
Still not try iRedAdmin yet. Working on Cluebringer support within iRedAdmin-Pro, hope to release a new version soon, so i have to delay Nginx support for some time. Sorry about this.
Also, i have an idea about Nginx support, not sure whether you guys will like it or not.
is it worth/better to provide an iRedMail addon package (another shell script sets like iRedMail)? You can install iRedMail first, it's a fully working mail server. Then you can run iRedMail addon package to install (and configure) Nginx and other components like Ejabberd, etc, then you can stop Apache and start Nginx as web server. Maybe charge for some dollars.