Not trying to put anyone off, but I'm not so keen on these. My mate had one on his LR, and the cross bars deflect a fair bit when loaded, like walking on them for example. This is due to the absence of longitudinal beams to form a grid and provide the support for heavy loads. It'll take them, it just moves a bit more in the process.
Me personally, I prefer my kit over engineered where possible. I've have had two Ali Survivor roof racks on two of my vehicles and they have been 100% rock solid.