Patrick has asked some opinion from Slackware-Current users in LQ about the performance of xorg-server 1.14.2 which currently residing in testing/. Some of the main reasons why it was placed on /testing was because it lack of driver support (ATI at that time) and also it is still causing some problems for some people.
Time passes and xorg-server gets minor improvements and it seems that most of the bugs has been fixed and there has been a proper driver support for both ATI and NVidia for the default kernel used in Slackware-Current (3.10.x branch).
I, myself has been using the xorg-server 1.14.x since it was released and it was working fine here on all of my machines (desktop, workstation, laptop), so i had no problem of it. Some other people also say the same thing.
At the end of the thread, Pat is considering to move xorg-server 1.14 back to the main tree and move forward with it. It's not happening yet, but i guess it should be on the next batch of update.