Well, all I can do is praise my Metz 48AF-1 flash. The Germans know what they are doing.
I had a couple of Canon 550ex, which were great flashes btw, but were very slow to recharge causing many a missed shot.
Anyhow, I upgraded most of my equipment over Christmas and in the process purchased a Metz 48AF-1 with the intention of getting a second "master" type flash later or the new yn-603's.
At the time the Metz 48 couldn't act as an optical slave however they just gave it the capability with a recent firmware update. Now I can trigger the flash off camera with my popup flash or otherwise. The flash works flawlessly and has a very fast recharge rate. Very impressive Metz.

