Motion sickness mostly solved in Hydra walking environment

For me, it's the speed of the left/right (turning) motion that determines motion sickness. If I move left/right either very quickly or very slowly (via mouse), I get little to no motion sickness. If I move using the keyboard and it's in-between speed, I get motion sick as my eyes try to track the environment. If it's a very fast movement, my eyes don't have a chance to track the movement and don't get sick, and if it's very slow, they have no issue tracking. Kind of like if you're in a car or train looking out the side window and watching things close to you fly by vs. things in the distance.

You're hydra setup may just give you more natural turning left/right to where your eyes can track it without getting you sick.