Not first hand experience, but good recommendations. I haven't taken a course there except my Cambridge Advanced diploma examinations. My lindy hop teacher (a Suisse romand) used to take lessons in german at the IFAGE. It seems it was a good base: since then he has been teaching a while in Winterthur. So far getting along well in the german speaking part.

Of what I heard from another person she was happy too with her course, not related to language learning however. All these experiences date a few years back.