Thanks for your quick and detailled reply! That helped me a lot to orientate myself :)

I tried to address your feedback and started a second rack version:
ModularGrid Rack

Just a sidenote: I already have an Arturia Keystep Pro that I plan to use as an alternative to the ES-9 if there is no laptop available.

For me it looks way more ballanced now, but I am still not sure, if there is something essential missing?
So it would be really nice, if you could again have a look at it. Thanks in advance!