I have the rift. i did get very motion sick after a few minutes (for like several hours).
Day 2 I still got motion sick for about 20 mins after about 30 mins gentle usage.
Day 3 mild motion sickness.
Now I don't get anything at all. It helps if you don't get all crazy with the moves when you first go out.
Looking straight ahead and gentle banking. The more you use it the less motion sick you will be.
Also if you can get a small fan to blow in your face to offset any heat from the mask and it also helps with motion sickness and also fogging of the lenses.
It's not too terrible and it goes away. Some say candied ginger also helps I haven't tried it.