The team that builds my client is exactly like this, the most humble group of people I have ever known.
As far as this whole mini zap thing, just stick to what is tried and true. It’s interesting that someone mentioned the devs not being a charity when that is exactly how they should approach this issue.
Let me explain, say you go to a charity dinner that is $500 a plate. Now, obviously there is no amount of food, unless it’s gold plated, that is worth that kind of money. So, they usually offer some form of reciprocity, like hiring a well known band or a comedian for the dinner. This allows the person paying the $500 to feel a little better about his/her donation while also only costing the person running the charity a small portion of what they brought in, it’s a win win.
So, when I say tried and true, primal is probably the closest to this method, as they offer you some extra features for subscribing to their project, which helps keep them running and makes the user feel like he is being appreciated for his donation while also showing his/her support for your team.
Basically, whatever Damus does, do the opposite, because holding TestFlight builds hostage is not what TestFlight was meant for and charging someone $50 for a hat that cost no more than $3 to make and trying to justify it by saying you have payroll to cover, is not only moronic, it’s a bullshit way to treat your users.