aakk9999 - 4:05 pm on Dec 4, 2012 (gmt 0)

From what you are saying above, it seems that Google only rewrites your title when the visitor is logged into Google.

If the traffic has dropped just because Google rewrote the title, then you should see this drop only within visitors with the keyword being "Not provided" as only these visitors would see rewritten title.

I think you should look at this angle before concluding that the drop in visits is only because of the Google title change - just in case there is something else that contributed to the drop in your traffic.