- Using the Backup site collection feature in the central admin on your beta platform, back up the entire site collection that contain you web or you list (dont try to' export only list or webs using powershell commands, it simply doesn't work (version conflicts).
- Using the restore-spsite powershell command to restore your site collection on your new platform...
- Yessss! Now you have you data on you new platform.. YESSSSS, it feels already better... (OOOH Damned.. I have lost my term store connection, arrrg)
- use the Content deployment wizard tool of Cris O Brien (Sharepoint MVP) to migrate content from your site collection to your new site. In my case I only had to migrate 3 big lists with content types.
I'm sure it can work without doing that but I didn't find the way !