We just returned from our long trip in the VW Trakka T5 from Blue Mountains NSW to South Australia via Cameron Corner, Strzelecki Track, Gammon Ranges, Oodnadatta Track, Painted Desert, Coober Pedy, Gawler Ranges, Eyre Peninsular, Melrose, Flinders Ranges, Murray Sunset NP, Big Desert, Murray Valley, Snowy Mountains and back home. We met some people at Coward Springs who have a very early version of your rack (no ISI cutout) and are still very happy with it.
The rack behaved perfectly, no rattling, it was solid and unshakeable over hundreds of kilometers of very rough and corrugated track. Nothing broke, nothing went wrong, it just handled everything without issue. A very tough and solid rack. Very easy to lower when accessing the tailgate, easy to remove on the odd occasions we did this. So a very boring review!