After you have successfully installed your AutoCAD 2016 products. You launch the software for the first time and get a Migrate Custom Settings dialog asking if you would like migrate you custom settings from the previous version. In the past we recommended against this due to issues from previous versions. But I have also successfully migrated clients custom settings in the past as well.
Recently, I found a post on the Autodesk website and it discussed how best to handle migration and how it was intended to be used. When and when not to migrate from one version to another.
This caught my attention and if you are considering migrating this is a must read.
Migrating between computers:
You cannot use this utility to migrate between computers. No files are exported or saved that you can move to another system. To migrate settings between computers, try the following methods:
Migrating from old to new computers: see link
Migrating settings for newer programs that cannot be used on an older computer system: see link