As the V6 has pass-though TTL etc I suppose it is meant to be used on-camera with a flash on top, if you need such a setup. I had my doubts they would be strong enough since flashes are about 1 pound / 500g with batteries. Weight that will be tearing on the Cactus and the hot shoes.
On the 3rd wedding I used the V6 it happened. The lower hot shoe of the V6, the one with the locking lever, broke off. The Cactus and my flash smashed into the floor and only the hot shoe plate was left on the camera's hot shoe. I did not hit against anything - it was just the weight of the flash that broke the V6
At the same wedding another V6 broke a little later. This time the receiving flash that was mounted onto light stand with the screw mount. This screw mount was suspicious to me from the beginning. It sits too far in front of the flash allowing for permanent torque/torsional momentum by the unbalanced weight of the flash. The light stand was moved around quite a bit but again - never fell, never hit against anything. The pure weight of the flash bent and loosened the screw mount of the V6 and I had to take off the flash before it would hit the ground, too.
I don't know if anyone else observed anything like that or if I had just very bad luck with my V6. But I honestly did not expect them to be THAT weak! They look and feel quite good. They are quite promising on paper. Unfortunately not durable at all for professional use. After only owning them for 3 weeks, 2 of the 3 I bought to test them are broken.
I would like to hear if anyone else had problems like that and what Cactus says.
Happy new year!