If done "right" it won't cause havoc with permissions but it may cause some applications that may have referenced the old home dir name in preferences and elsewhere to "break".
The general scheme is to change the pointer to the home dir in the Accounts and to change the directory name in /Users/accountName.
If it were me I would log into another admin account or root so you are not actively using the account who's home dir name you are actively changing. Thus you are effectively changing the home dir name and the pointer to it as "the same time" as far as that account is concerned.
I've never actually tried this. But I always move keep home dir on a separate volume from my boot volume. This is basically the same except for actually moving the dir. So I believe it will work.
As I said if you been using this account for a while you run the risk of breaking a few preferences but that's not too major. I never have that problem because when I set up new machine I move my home dir as shortly after it is created so there's no preferences that can break.
And finally, don't attempt this without bootable backups of everything involved. Use a backup utility like Carbon Copy Cloner to create bootable backups. Then if something failed you can just copy the bootable backup to the original disk and you are right back where you started.
