I rode the Vitas last year. It wasn't a problem. Didn't notice anything problematic.
I think the reflex is designed to flex with the board. When you're pressing forward like in the video, you'll actually be up on edge, not flat on the ground like that. I think it'll be minimal.
Exactly this.. Its just something new that you have to adjust too. Even on the flat of my carpet, it doesn't feel loose or like there would be a lack of performance. The bindings feel good overall. I didn't mean to try and steer anyone off of their picking up Re:Flex bindings. I think they will be badass out on the mountain.