I am using X over ssh as well = great. I use linux or MS Win(Xming package + putty) on my workstation.
Do you really need to do all that xhost/export stuff? As long as you've got xauth installed on your plug and made sure your ssh client and server forwards X, you should only need to ssh into plug and launch the X apps.
Make sure you've installed xbase-clients package:
$ apt-get install xbase-clients
If I were to use anything else, I'd try NX over VNC; so much nicer and it runs also over SSH tunnel.
I saw the below link, but I haven't tried ithttp://computingplugs.com/index.php/Installing_FreeNX_server_and_NX_Open_Source_Components
Since NX visualizes a whole desktop session, it will be more resource intensive. Therefore I am happy with just X/ssh.
Also, it allows me to explore some nice ncurses based apps for lean and mean computing, for instance screen/rTorrent client etc.
I use NX all the time between more powerful machines and the one thing that is really nice is that you can resume desktop sessions, which is an advantage over x/ssh.