SSL/TLS are unavailable at this time, which means you're exposing your data in transit over the Internet. It’s perhaps workable in an informal darknet as long as all the users use good operating practices and none are “bad guys.” There's a plug-in that will fill in a robots.txt file to prevent a server from being indexed by search engines. It’s workable when detached from the Opera server on an internal LAN as a webserver/fileserver and *media server, as long as access from outside the network is firewalled and/or blocked at the router.
An Opera representative told me that the proxy should be left at operaunite.com, so the proxy address in opera:config should be left set to the operaunite website default.
Generally, as long as you access the services via http://192.168.1.10:8840 (or whatever the actual local IP/port of your setup is), the proxy should be a non-issue for normal operation. To check this on any given service that serves up files, simply mouse over the file link. If the link that shows in the browser status bar has operaunite.com in it, the proxy is an issuei.e., it’s sending a URL to opera when a file is accessed (see Figure 7). Whether this is a problem for you or not is something you have to decide.
Figure 7 Unaccounted Opera website access
There are accesses to Opera sites when a service is started (monitored with iftop). Its developer documentation specifically states that the only use for the username.operaunite.com web proxy is to make it possible to access content a user wants to make available to the public through a user firewall/router without having to type :8840 after the URL.
I was disturbed by seeing accesses to the Opera Unite servers even in the full privacy mode. I explained that setup didn’t make sense to me. (The above happened when I was doing admin stuff with Media Sharing.)
As can be seen from the Firefox page information display in Figure 8, several images on a content server page are hosted on Opera websites; from the URLs, I'd guess they're hosted on the developer pages so the developers can find out where their services are being used. It appears, though, that there is no way to find out what content of yours is being accessed locally by your users via their services with the setup described here.
Figure 8 The mysterious webaccesses revealed