SyncKolab was written to add kolab functionality to thunderbird. It reads a selected Imap folder and synchronizes it with the local address book and calendar.
Version 1.0 had 61 prereleases and 83 nightly releases with over 100 bugs fixed and is known to work nicely with Thunderbird 2 and Lightning 0.8.
Even with this extensive testing, there might still occur problems in combination with other extensions, operating systems, thunderbird versions and/or special characters in your contacts/tasks/calendar entries .
Because of this, you should make a backup of all your relevant data (server side or your profile directory) before doing your first sync. If seomthing happens because of a bug you can then easily restore your data afterward.
If you find any bugs please check the synckolab bugzilla on: http://synckolab.mozdev.org/bugs.html