My Gmail Contact Sync did not go perfectly either, however What I have found is.
After the you enable, give it about 10 - 15 minutes to sync with Gmail, this duplicate your contacts more then once...
Once you noticed your contacts stop duplicating log into gmail, check your contacts and merge all you duplicates. Then give it a few hours to sync back up and then your issue should be resolved, That is what I did.
once I got past that initial hurdle the contact sync has been fine and perfect. In some cases new contacts on the BB have been added to Gmail instantly.
8830 -> 8330 -> 9550 -> 9650
Just think about how far BlackBerries have come from then till now... And what else is coming.
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