I am using Kubuntu now, and hava partition as /home seperate from /. I want to install xubuntu instead of kubuntu. Can I do that without affecting my files at /home and is there any disadvanteges of doing so?
I disagree, you should be able to install xubuntu without formatting the /home partition. Very few, if any .files will conflict between kde and xfce.
It has been the default behavior of the Ubuntu installer (ubiquity) to preserve /home, with or without a separate partition, for quite some time, .
The general concept of backing up your data before you install an OS applies, but, you should have a backup already.
When switching to another OS you have to take in account that this OS can (will?) have other names for hidden directories or files that store configuration files.
A re-install with formatting /home is the proper method.
Any other method might result in a system that has residual files from the old OS and you could potentially run into trouble when the new OS uses a file name that was kept from the old system. Permissions could prevent the current OS from updating a file.
Possible pre installation options:
The text starting with "few people" from bodi's post only should apply to Ubuntu as is says in the text. If you want to switch to another version of Ubuntu it can (not saying it will!) cause problems. Thing is: next person will assume that Mint is Ubuntu and oh is he in for a surprice. A big one.
Another example: let's assume you switch from a GDM/Unity based version to a KDE based version. You probably will end up with lots and lots of files not needed for KDE and owned by another users ID. Assume you create a new user for that new OS and it probably will not go as smooth as you would expect. It is asking for trouble. The -best- practice is a re-install with format.
No, I see lots of possible(!) problems. But ... of course you can always try and do a 2nd install (that way you get to learn more from installing).