i doubt its really designed for non stop use. It might not weigh much, but for hours on end it will strain your neck and eyes i would think.
Also or alternatively, a good-sized, well-sealed helium balloon can lift 50+ grams...
https://support.oculusvr.com/entries/24808208-Will-the-Oculu...
I do hope their statement is correct, but it sounds too good to be true.
I think this is the really surprising thing for people who haven't tried it before -- you think it will be like looking at a screen up close, since you've looked at screens your whole life, but it's nothing like that at all.