As read here has me smell initially deterred to use the flash. Only after a few days of "airing" I did the first experiments with the flash.
One thing is clear: for the called tariff there exactly what I expected. Universal and especially überschauhbare technology kostengünstigst packed. As a "rarity" for all brands fit naturally there no system contacts. The flash with the indicated guide number 32 is pivotable. I count as a plus for the DBK. I also find the flash off when 30mm and slightly lower still good enough. The illumination has also surprised me in the uniformity.
The flash is adjustable in eight steps. In TTL mode, the DBK may also automatic. Class is the built-in sensor. This allows the DBK used as an additional light source. I too have the DF 400 used as fill and am quite happy with the results.
My conclusion: For certain situations the DBK can be a cost-effective alternative. For the high demands of Mitblitzfotografie or a genuine alternative to dedicated flash per se but not reichts. But he is also not intended.