Careful with the Rackbrutes if depth is critical, though. The maximum depth that Arturia lists is a "best-case"...the actual limitation over the power bus is more along the lines of 45mm.
Also, consider that you're not likely to be swapping out a case along the lines of that Structure (it's also not the only one in the line, as well). You won't exceed the power supply limits unless you chuck a pile of Metasonix modules into it, for one thing. It has the form factor you want, also.
When building a system, it's VERY advisable to work with a case that's "larger than you think is necessary"...because, invariably, it's NEVER larger than you think is necessary. And getting stuck with a smaller cab becomes a big pain when you outgrow it, because then you have to go with yet another case to gradually populate...but while that's happening, you've got a second big clunky (and spendy) box taking up space, for the most part. Starting at some point that seems too big, ultimately, results in a pretty comfy system to build and work with.