There are a dozen of brakes available on the market and I noticed that each one as a different opinion on what brake is the most appropriate for slackline.
To be honest, each brake has his own good and weak points. Some are compact but weak, so are strong but heavy, some other are hard to find. The perfect brake for everyone does not exist but all can do the job.
Here is a short comparison of the most frequent brakes used on the field
There’s certainly a lot to learn about this issue. I love all of the points you have made.