After having first browsed this forum before upgrading from LB5 I did so with some trepidation after reading about some user's issues. But after using LB6 for a few days now and having adjusted to the new themes, I am very happy with the upgrade. In fact, I upgraded to Mavericks just so's that I could run LB6.
I suspect the issues others are having with the upgrade can be caused by old caches. The upgrade procedure I followed was to quit LB, in the Finder navigate to ~/Library/Caches and search for the name "launchbar" and delete every result that was inside that folder. I then installed and opened LB6, tweaked the preferences and index, installed more actions, and it has run smoothly ever since. And that is with the same ~/Library/Application Support/LaunchBar folder contents and preference file since 2004, which no doubt contain a lot of cruft.
I suspect the issues others are having with the upgrade can be caused by old caches. The upgrade procedure I followed was to quit LB, in the Finder navigate to ~/Library/Caches and search for the name "launchbar" and delete every result that was inside that folder. I then installed and opened LB6, tweaked the preferences and index, installed more actions, and it has run smoothly ever since. And that is with the same ~/Library/Application Support/LaunchBar folder contents and preference file since 2004, which no doubt contain a lot of cruft.