The promise is fantasic. The design is very, very poorly realised.
1: The case is 'upside down'. It's practical the doors open above than below. (I use mine upside down)
2: No extra screw plates (10 cents extra, Gator..?) for the rails on the rear to attach equipment on the rear side, ie: Patchbay, powerboard etc. (I invested in my own solution for this)
3: The rails on the front side are not deep enough to protect the buttons on your equipment. This is a major flaw. (The case is supposed to protect your equipment..!)
4: Today, I notice a small hole where the stiching had come apart (only used so far at rehearsals). This I can forgive as QC in manufacturing can happen (Thomann - I will be returning for a replacement)
Unfortunately I need to live with this as it's the only 4U with wheels I've seen. If there's a similar alternative available I recommend considering it.
Unfortunately its's a great idea, just poorly executed. A working musician would have noticed these things immediately. I'm guessing it was designed by someone working in an office who's not a musician :o(