Yesterday I took wheels for a proper ride, bit of a climbing, some flats and a long descends, all in a winds with gusts up to 80 km/h. Wheels are definitely on the stiff side, my bike is already very stiff so I felt a difference compared to my previous carbon wheels. Road chatter is easily picked up and you can feel it on your hands, especially on the hoods, but not that much in the drops. Sidewinds do affect the wheels but not that much and this is what I really cannot fully confirm. I felt few wind pushes from the side but mostly the wheels are balanced and stable. On the flats they roll nicely and I was able to hold my power around 350W and maintain a speed of 45 km/h with compact crankset (34/50). During the descends wheels are nice and they are not twitchy.
I am not a pro rider and I didn't tested a ton of other wheels but I can say they are worth the money and they are upgrade over my 1000 EUR wheels. A bit on the stiff side but that could be good thing. No problems so far and I also backordered a few spare spokes from Matter.