Hi Verross2,
according to marco’s post I am able to give you some information regarding the Vive.
For my masters thesis I created a VR app and also did an evaluation with 20 people who have none to little vr experience.
Evaluation was about multiplayer-, performance- as well as interaction-related issues, but there has been an interesting sideeffect:
Two of the testers were < 10 years old. They found some interactable features, like menues or objects were placed to high for them to reach, as the app and all elements were designed by me (183 cm).
Another tester was around 210 cm tall. She experienced some kind of fear while going through doors. she was afraid to hit her head. She was also able to stick her head through the roof sometimes 
As you can see, the Vive tracks the height of the headset while playing and applys it to the pawn in game.
hope this helps you!