The only downside is that Hetzner does not allow you to set a limit to control the egress traffic expenses, does it? So that you can be protected against the so called "denial-of-wallet" attacks.

The "usage" tab allows you to set a euro value limit on each project for an email warning. I just use that. It isn't specific to egress, but total accumulated usage for the project.

Didn't know that, it's nice. However, it would be perfect if they would allow you to set a hard limit to stop your services automatically, because it can take a while between you reading the email and logging in to stop your machines.