i own both the metz 45cl-4 hammer head and the metz 54mz-3. both have its disadvanage and disadvanage.
metz 45cl-4 :- heavy.... you will be tired off if you shoot with this the whole day. lighting kind of a bit unbalance cos is not place in the center of the camera if mounted on bracket. good for bounce flash....espeacially in low ceiling room.... and very good for table to table shoot-out during wedding dinner.
metz 54mz-3:- lighter than the hammer head. zoom head give good long range flash shots. a bit poor in dim ball-room shooting unless your shutter speed can goes as low as 1/20 or 1/15 at f5.6.
so.......during covering weddings....day time with metz 54mz-3 and dinner with metz 45cl-4...unless i know that the dinner arena is a super-bright one.