First note that on upgrade from previous ZD beta builds: Existing tasks, documents, and briefcase items don't get immediately downloaded because we use a mailbox wide change sequence. However, edits or moves of existing items will trigger sync. (Obviously full reset of account data will also pull in old items as well.) This is a one time issue when we introduce new applications to desktop. (If really wanted to we could grab old, but since that only affects those coming from ZD Beta 2 and earlier in regard to tasks/docs/files it wasn't worth the additional code complexity to address it.)
I could test versions for ya, but I'll wager you need to upgrade. ZCS 5.0.5 came out in March 08, and ZD B3 was 4 months later in July directly between ZCS 5.0.8 & 5.0.9 releases. From that bug it's evident there's version dependencies because of server side changes that needed to be made.
When the server version is 5.0.6+:
- downloads only the latest version of Notebook and Briefcase items from the server
- uses soap API to sync notebook wiki pages
When the server version is 5.0.9+:
- downloads all the revisions for Notebook and Briefcase, so that the edit history is also in sync
- can detect edit conflict for both WikiItems and Documents
- uses TarFormatter and more efficient REST interface to sync documents and wiki.
Lots of other good enhancements and bugfix reasons too upgrade to 5.0.16 anyways. | 
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