Yes I have a lot of contact and calendar data and all of that syncs properly in both directions (using the same Kolabnow connections). Only the calendar “Tasks” is affected and that only in one direction:
Within kolabnow a user is able to (un) subscribe folders. Calenders, Task and Contacts are “special folders”. So if you unsubscribe within thunderbird from this folders (imap sync), this resources aren’t propagate to davdroid as well.