I've migrated the old workroom to CMS 5 successfully. The tabstrip webcontrol is placed in episerver.legacy dll and is set to obsolete. The user management must be rewriten and all property updates must use createwritebleclone.
I also created a small win-app to convert the comma-separated propertystring with all sid's that is placed on the workroom page.
Has anyone successfully migrated 4.62 workrooms to CMS 5? How did you go about? Did you migrate the code or use the new workroom templates and adapt the data? Any big problems?