I do it often, it works.
I am computer technician, fixing my client's hardware and software. Also my own computer. I regularly upgrade my computer, format/install/re-install my hard drive. Once in every 2 years, but sometimes 3 times in a year.
I backup and keep my Lazarus' config files, especially:
- editoroptions.xml
- environmentoption.xml
As Thaddy said, copy the configuration files. That should be okay. But in some rare cases, the Lazarus won't start or it can start but cannot be rebuild. That happens because the config file (packagefiles.xml if I am correct) has one or more packages that aren't installed on the newly installed Lazarus. But that wouldn't be hard to fix, because all the config files can be manually edited using a text editor.
I use Linux.