This blog article describes how you might synchronise Documents between SharePoint 2007 and SharePoint 2010 with Data Synchronisation Studio including custom Metadata columns whilst preserving the Created and Modified Timestamps and user accounts.
Here we have a Document Library in SharePoint 2007 with a few Documents and a Folder where going to Synchronise this to a new SharePoint 2010 document library.
Here's the Empty Document Library in SharePoint 2010 which will be the Target
To define the project in Data Synchronisation Studio we need to use the SharePoint provider for SharePoint 2007 and the new SharePoint Client API provider for SharePoint 2010. Connect Data Source A to the SharePoint Provider
Connect Data Source B to the SharePoint 2010 Client API Provider
Configure the Schema Map like this and add any other meta data columns you also wish to synchronise.
Ensure that the Document Library Update Behaviour is set for FileAndMetaData on each side to that the Documents are uploaded.
Run a Compare A->B and Synchronise the Documents
And now the documents have been synchronised including the Created/Modified Timestamps and User accounts.