Have any changes been made to the layout/use of the UserSettings folder?
That is; Is it safe to copy the old one from V27 and replace the one that comes with V28?
I've used the same Usersettings folder I made in V17 and it works great! I've copied it to a new computer, reinstalled Civ and Windows, and it has still worked for all of this time. So I'd say don't worry.