It's usually 2mm. Hyperx's own red switches have a 1.8mm actuation distance, but both are practically the same.I am not sure about the activation distance for red switches
I suppose feathertouch means easy to click without much force needed. I've never heard of feathertouch either. Perhaps the keys found on laptops or as mentioned earlier, LP keyboards are what OP means. I recall Roccat having an LP keyboard. Only for the keycaps though, not the switches.the activation distance is a significant and not what I would call "feather touch".