Just wanted to chime in as one who loves multiple rack spaces side by side as they are now. I would dislike seeing a separate rack in between various SSL channel strips. If they did add that feature, then perhaps keep the old way as an option for those of us who like it the way it is? I suppose if the visibility of the SSL-integrated rack was on a toggle, then I'd never see it. But how to handle the visibility of the rack from the back? I know they could be on a toggle as well, but the cables dragged across horizontally would be a nightmare, in my humble opinion. Software updates are tricky. They can add new features all day long, but it's near impossible to take one away without pissing off some users.
Perhaps this explains why I love the width. I used to have a few double wide racks back in the day and having as many as I want side by side now seems to make perfect sense to me. It just looks right (obviously, others disagree). All of my monitor displays are wider than they are tall, so it makes more sense to me in that regard as well. Because I hated scrolling vertically for days due to the limited vertical space I had for viewing, I would connect external displays to my laptop and physically rotate them into portrait view so I could see more devices at the same time. I don't have to do that any more.
I also love having a separate channel strip rack unit for each device in the rack view. That's what keeps the cables tidy, as long as they are directly above/below each device they connect to. I admit, it took a minute to get used to, but now I quite naturally view each channel strip rack unit as a shortcut into an SSL channel.
Definitely +1 for the elevated sub-group idea! That looks awesome! Not sure about the blue shading all of the time... maybe only when one of the channels is selected?