I bought the Vello for my D7000. Overall, I am happy with it because of the price. I thought I stripped the gear of the lockdown mechanism to the tripod mount when I was testing the tightness of the fit. So I took it apart. To my pleasant surprise, the gears are made of metal and are quite sturdy. There is a weak link however at the bottom of the plastic mold where the plastic locking wheel sits. The wheel has a metal axis and gear fitted in the center but the metal axis is resting on this plastic hole which is quite shallow. I could see that some of the plastic had gotten "shaved" off when the metal axis tried to move out of alignment. My remdy to this problem is to use 2 fingers to tighten the wheel from the front and the back of the grip so that the wheel doesn't pivot too much which will eventually strip the plastic recess for the metal axis.
The second issue that I encountered is that with the Pearstone battery in the grip. When I first put it in and got it connected to the camera, it recognised it without problem. I turned off the camera and turn it back on awhile later and noticed that the camera read low battery in the grip and the shutter is locked just like if your camera battery is too low. I thougth the grip drained my battery but it was not the case. I had to remove the tray in the grip and reinserted it and it was good again. I think it is the battery rather than the grip because I didn't have that problem when I swapped out the batteries and have the Nikon one in the grip and the Pearstone in the camera. Now, here is the other issue. Why didn't the power management switch the power source from the grip+pearstone combo to the camera battery when I got the message of low battery in the grip and locked up the shutter and I was left with no choice but to unplug the battery tray from the grip. Eventhough it might be due to a third party battery, I hope that it is not the grip itself not being able to switch the power over even when I am not using the 3rd party battery.