Apparently experimental.
I've used it many times without fail now.

When you do make a separate home partition, the partition which contains your old home folder must not get wiped. You must have your old user accounts home directory in the root of the partition.

Only issue I have had is when transitioning. If you make a new user name. On the log in screen, if you enter your password right it will try to log in than keep you at the log in. So if that happens log in as root.
Change the directory name to your user name and you should be good to go.

I found it easy if you already separated root and home partitions. Made it work very smoothly if you reuse your user name as well. Just make sure you point the installer to the right partition and it won't wipe it .

I don't know much  about having multiple users and different IDs so maybe it might not work properly across a different distribution. Although, your data won't get wiped. Although, I imagine on an lukscrypt it wouldn't be so simple