Review : FCS Premium Soft Racks Single
The sangles are situated head high and the car and it's pretty uncomfrotable.
You can't tie the soft racks enough so they do not move, and you can't strap the board too hard either, even with a board bag.
So what you get is a vibrating and moving system, that can make noise inside because of the straps and outside because of the rest.
This kind of system should be primarily and sensefully used for short trips to the beach. This is obviously not made for travel! They certainly should mention that.
I wouldn't go more than 60 mph. Certainly dangerous, even if it seems well built and heavy duty, at higher speed, in my opinion.