with this latest Cepi's dev version 1309 I can finally sync my contact list with more than 500 contacts successfully... it does give me "not responding" once, but continues briefly afterwards, and contacts are loaded... really delighted... all that with the old .db file too, so all chats and groups are saved... great job, guys!

EDIT: my mistake! started now from the terminal with the old .db file, and only those existing contacts are being fetched and loaded... deleted .db file, started it again from the terminal line and no contact is loaded...