Treadigraph: Depends on the route. If he flies direct to Friedrichshafen, as is now proposed, he will miss the really big peaks in Switzerland (which he will miss completely, oddly enough). Perhaps "miss" is a bad choice of words! In fact, the last thing you want to do in this region is to be VMC below a layer of cloud trying to follow the valleys and just hop over the cols. A number of people have found that to their cost recently. Once in Friedrichshafen they will have an easier bit going north. And they can take a Zeppelin ride while they're waiting. Incidentally they will just about overfly the home of the accompanying Pilatus.
Good luck to them.
Laurence