To get Leopard client to sync properly with Tiger server I have to add following six keys to com.apple.homeSync.plist:
<key>syncBackgroundSetAtLogin</key>
<string>dontSync</string>
<key>syncBackgroundSetAtLogout</key>
<string>dontSync</string>
<key>syncPreferencesAtLogin</key>
<string>sync</string>
<key>syncPreferencesAtLogout</key>
<string>sync</string>
<key>syncPreferencesAtSyncNow</key>
<string>dontSync</string>
<key>syncPreferencesInBackground</key>
<string>dontSync</string>