Well if anyone can tell you it's nintendo, but I'm suprised you can't do a quick and dirty "RedirectMatch" to help the SE's find the new urls.

Yes there will be a period where you have duplicate pages and Google will be a bit erratic about indexing them.

I had a similar situation, lost lots of pages, got them back again, lost them again...

Now it's rock solid stable with 3,000 pages indexed, but it took a couple of months. I don't know how long it will take for you because it depends on how many pages, how deep the pages are from the front page, how often you get spidered (PR) etc.

Cheers,
Paz.

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10.3 million entries for Hotels in Turkey but I'm still chipping away.

Thanks so much Paz and Nintendo! This forum is great. I very much appreciate both your time and expertise.