OK, here’s my experience with this.
First, I set the Max Altitude to 100ft and took off. I gained height until I hit 100ft and it just went on climbing.
I freaked out! Landed the Mini and checked my settings only to discover that I don’t seem to know the difference between 100ft and 200ft because I had set the Max Altitude to 200ft
I reset the Max Altitude to 100ft and took off again. The Mini climbed to 100ft and then stopped climbing. I saw no warnings from the controller and there was not audible alert (wasn’t sure what to expect) but she just hung there at 100ft.
I’m OK with this, it means I can happily set a Max Altitude and know that the Mini is not going to go past that if I take my eyes off the height. From a purely personal perspective I would quite like a warning or, given that the controller loves to chat, a verbal “Max Height reached” notification, or some such.
Anyways, that was my experience. From a scientific perspective it it would be great if another of our MINI owners could confirm that they see the same behavior?