I spent afew days last month playing around with my home server which has been using freenx. I tried x2go and the beta version of No Machines server, as well as the old version. Nothing worked properly.
I was able to get freeNX working properly. Admittedly this appears to be an OpenSUSE 12.2 issue, but I was able to find references to help me for freeNX and nothing was forthcoming for the other two.