Exporting and importing image fields is easy. How to export images uploaded using CKeditor in the body field of node? I have a view which exports the content from D6 (in XML format). In D7 i have feed importer which imports the content. I can add all fields in view and get all data exported. This works well for everything except images placed in body field. They don't get migrated as it is not part of node field.
You can get the uploaded files from the D6 files directory, and upload them to the default directory that CKEditor is set to use in D7. When you import those nodes, you can either change your XML source directly, or use the Feeds Tamper module find/replace plugin to rewrite the paths in the body field to the new location.