But that means you would leave part of the wall (red) in place?
Question (especially to those with positive experiences): How does it behave with noise and the soundscape? Doesn’t it echo extremely loudly upwards into the bedrooms?
It depends on what "extremely loud" means to you. It doesn’t just echo upwards, but also downwards (the issue of loud music from children with open bedrooms).
It is not as loud as with an open gallery. That means you don’t have to speak quietly downstairs for the children to be able to sleep with closed doors. Music at a moderate volume is also okay. I simply have no comparison of how it is otherwise.
If the children are loud upstairs, they should close the doors. That’s how we do it! Loud to me means it’s annoying because the children are shouting around.
But one thing is also clear: sliding doors made of glass (wood is a bit better in this regard) don’t seal anything at all.