Hi Josh,
Since they can see the reward in the Crowbox I would expect that birds are less startled by any noise or movement, but this seems to vary a bit with the type of bird. I get jackdaws and haven't had a crow come by in months. While they started out very wary of approaching a new thing in their environent, they overcame that in a couple of weeks and now seem to associate the sound of the dispenser with imminently receiving a peanut. It would be interesting to see if birds learn to associate the noise/movement of uncovering the peanuts in the Crowbox with reward as well, and if they behave differently when they can see the reward in advance.
On their approach, do they eventually move from exploratory behavior to more deliberate behavior? Do they continue to inspect the device after a few interactions? When fresh coins are provided does this attract them? Once the door is open, do they hesitate or just grab the reward and how many peanuts do they typically take?
I would guess that the servo-driven sliding door makes less noise than a vibration dispenser and is more reliable, but it does allow birds to swarm and grab lots of peanuts once one bird deposits a coin. This, along with clearly showing there are peanuts inside might be helpful in drawing a larger group of birds at the expense of providing more peanuts.
There are so many different designs and approaches to this, but I don't have much luck finding videos of birds interacting with them other than Tomas and Olaf Morsing and Hans Forsberg. A lot of people on this forum have built Crowboxes, so I imagine a few of them have some interesting videos to share.
Steve