Until Creole rendered implemented, switching page syntax to Creole is to be discouraged

it's akin for double conversion

Imagine user makes rich xwiki-syntaxed page, changes to creole (some markup is from now on just text), founds GUI editor dysfunctional, switches back to xwiki (escaping that just-text which now matches markup sequences) and - here he is.

I think if there is something you can not stick into Creole, then switch should better not be permitted. Let user simplify the page 1st.

Also there is to be a warning when switching Creole->XWiki. User should be alerted that he got a one-way ticket