Second ride report, went on a group ride tonight and they performed fantastically again. Did a lot of coasting because they hold speed really well (even when riding outside the group). Mountain climb and descent with no issues. Hard on the brakes after a long fast section at the bottom of the mountain, stopped and felt the brake tracks, barely warm.
Not sure if it's the grooved track, or if this is just how Swissstop pads are, but I don't think they're going to last very long. But maybe that's just the price you pay for good carbon braking.