Sharing Thunderbird Address Books... some experience

This is a follow up to my post on Sharing Thunderbird Address Books Between Computers with Dropbox.
I've been using this for 3+ weeks now, and here's the experience.

Overall it works quite well, however:

1. I noticed 2 occasions where the filesystem link from the address-book in the Thunderbird profile to the one in the "My Dropbox" folder got lost. The abook.mab in the profile folder then all of a sudden is a real file with not connection whatsoever to the dropbox file.
   
2. Dropbox deteced one replication error and marked it accordingly, by renaming the "older" file as "abook (computername's conflicted copy date).mab"

In both cases replication of the file to and from other computers then fails.
The latter is easy to avoid - at least in my case: Don't have Thunderbird open at the same time on both computers.

Sometimes however, this is tricky, because you need Dropbox to replicate the file before you start Thunderbird on the other computer. So e.g. when you hibernate one PC whilst Thunderbird is still running (keeping the abook.mab file open and locked), the file will not get uploaded to Dropbox. When you then start Thunderbird on the second computer and modify the address-book... voila... replication conflict.

I still don't know what caused the link failure from problem #1. Will continue to monitor this.