I am using both slackware current x86 and x86_64 theses are checked updated daily.
The x86 build seems so much more stable in the kde environment. the system as of the 01-02-2011 updates both systems are very stable but the x86_64 always seems or has kde blips. like phonon and . I am a huge fan of the x86_64 system and use it most of the time. But the x86 build has given me less glitches.
That all said and done they are both very stable and top shelf in my book.
Any other people noticed this in some of the builds chime in.

Just to be clear, you are saying that you experience some glitches when running Slackware -current on x86_64? What exactly seems to be the problem?

many of theses are caused by the evolution of changing versions of software and there dependencies. So from a none tech way of saying this. I will say grab the latest mirror and and do a fresh install of both x86 and x86_64. phonon it was very nice and smooth in x86 but the x86_64 would after install and running with user 1001. user 1001 would reboot. this would cause My HDA sound to be detected digital and analog. Kde would then ask me to rid of the digital as it should but has caused some people to ask why and then it repeats the problem every so often.
this never happens in x86 build.
I also notice pre 01-02-2011 update that my users with dell Intel CPU SMP x86 systems have been crashing the xorg when running flash. Since none of my users
are using x86_64 at this time with ATI I am unable to gather data on the x86_64 ATI. The xorg crash is real on the ATI cards with the 12-28-2010 mirror.
this both happened in xfce4 and kde4.
this is not happening with the nforce nvidia setups.

I think we found the x86 problem from here at LQ great work.