I have a CentOS server that currently has no X server on it. It will be used for doing statistical crunching and providing other services (probably via a web interface). The main security for the box is provided by VPN.
Some of the users will need software that can't function without graphics. I'd rather not make even a minimal install of an Xserver and window manager, but if I do so I was planning installing X, a lightweight desktop or even just a window manager, and VNC. Users would connect to VNC sessions via ssh tunneling. One big advantage of this arrangement is that if the network connection drops, whatever is running persists instead of dying.
For persistence, people in operations suggested I look into using xpra instead. I did a dry run of an install, and it installs an X server, so at least on its face I don't see any advantage to this approach, either in terms of security or simplicity.
Is there any security reason to prefer the xpra approach over VNC+Xserver+ssh tunnelling?