If you use the export link to move your posts to anew server.
Stop right there
If you use this function it changes all your post id,s
So if you already have pages in google such as blahblah/234 it will change to blahblah/36 or whatever
As you are changing servers you keep your permalinks the same.
I have just had to redirect 301 70 posts, as if you write a post in your new location and your next id is 91 and you already have Post out there with id 91 your old post will now point to the new one regardless of the title of the post.
Just my bit to keep from have to go through this bloody hassle.
My fix for this was to change the old permalink structure from
to /%postname%/%year%/%monthnum%/%day%/ thus taking the ID out of the loop and then redirect all the old posts that were in googles index to to the new permalinsk structure
If any one has a better idea i would like to know..