Just for fun (and because a rack might work in my drum room) I ordered the 4U unit. The first thing I noticed was that two vital screws were missing, rendering any assembly impossible. A mail to CS took care of it and they sent a replacement unit (6U) since 4U was out of stock.
Granted the new unit had all screws necessary, now it became clear that the top bar on both the 4U and the 6U unit were of different length – none of which could be mounted since too short. Fair enough one might think, since the top bar could still be omitted as it blocks space for potential top units, and stability is inherent when adding gear anyway. Then it became clear that the main bar in reality is too long since none of my 19" units would fit. The whole rackstand is too wide.
So currently having two useless stands. Luckily I only paid the equivalent of a lunch, but still. Having spent more than 30 000 EUR on gear from Thomann over the years this was a low point.