Xan wrote:
I'm having trouble thinking of "manual maintenance stuff" that would require a GUI at all.
Synaptic Package Manager?
Running a GUI will have a noticeably negative effect on the performance of your server, though it somewhat depends on what kind of GUI you run.
Most server programs don't even have a GUI in the first place, let alone require one. You'll most likely find yourself opening the terminal anyway if you were to do any real "maintenance stuff".
If you want to browse the web from your server, install a proxy server (such as tinyproxy) and set your home browser to connect through the proxy. I think it will work with localhost as well if you configure it correctly.