Yes, but you can remove the admin interfaces for the public facing servers by modifying their episerver.config.

Frederik

You might also have to keep the "Public" interfaces for EPiServer Mail because those are used when tracking opened and bounced emails etc. The "might" depends on your configuration for EPiServer mail, you specify the full URL:s including host in the episervermail section of your configs. So it is possible to route all such requests to the edit server though I would recommend using the actual site URL (to the load balancer) and keeping the parts of the EPiMail interface needed on all servers. Basically the /episervermail/public folder should be enough but I have never tested to remove the rest of the folder structure.

Many thanks for your comments - This will be interesting :)

Another complication has been raised; the 2 Live servers will share a single database.  presumably this means that 2 Mirroring Channels will need to be created - how to prevent the database being written to twice?

Regarding CMO, you can try this approach:

1. Install CMO Core, CMO UI and Statistics handler on each load balanced servers. Create new CMO database when you are installing CMO on first site; use existing CMO database when you are installing CMO on all other servers. So you will have the one CMO database for all sites/servers.
2. Since URL of Thumbnail service is shared settings for all sites, you can have Thumbnail service installed only on one machine. Thumbnail service should be accessible for all load balanced servers. And and vice versa - Thumbnail service should be able to access your site to make screenshots. Make sure that secret key in app settings is the same for service and all sites.
3. Manually install CMO Aggregation service on one server, probably where you have databases. Point Aggregation service to CMO database for your sites. See details here: http://world.episerver.com/Documentation/Items/Installation-Instructions/EPiServer-CMO/CMO-2-R2/Installing-Aggregation-Service-for-CMO-20/
4. If you want to use CMO admin UI on all servers, make sure that load balancing server is configured to use sticky sessions.

More information about CMO configuration:

• http://world.episerver.com/Documentation/Items/Installation-Instructions/EPiServer-CMO/CMO-2-R2/Configuring-CMO-2-R2-to-support-NET-40/
• http://world.episerver.com/Documentation/Items/Installation-Instructions/EPiServer-CMO/CMO-2-R2/Configuring-Live-Monitor-for-Multiple-Bindings-in-EPiServer-CMO-20/
• http://world.episerver.com/Documentation/Items/Installation-Instructions/EPiServer-CMO/CMO-20/Configuring-the-Thumbnail-Service-on-Windows-Service-2008-R2/
• http://world.episerver.com/Blogs/Dmytro-Duk/Dates/2011/5/Page-thumbnails-in-EPiServer-CMO/
• http://world.episerver.com/Documentation/Items/Installation-Instructions/EPiServer-CMS/Version-6/EPiServer-CMS-6-R2/Installation-Instructions---Live-Monitor/

This is great info - thanks

About mirroring - as mentioned in the Mirroring technote "The Mirroring application can even be hosted on a totally separate machine to the source and target sites." (unless you ar using legacy mirroring).