Bart ,
Contrary to what many think, Tyvek is a sub brand of Dupont (like say EOS cameras for Canon or Bravia TVs for Sony) NOT a single product.
Each of the many types of Tyvek has different characteristics (they would not make over a dozen all the same, would they...) and the type used for bivvies is not the Home Wrap but the soft/cloth type (also called kite type) like the 1443R.
Some will use the Home Wrap version for the bottom because it is somewhat waterproof and has better abrasion resistance.
The 1443R breathes the best.
I am pretty sure the one you linked to will not breath the way you think it does (it might be very breathable for a house not a human body...)
Here are 3 types of Tyvek I had on hand :

two HomeWraps and the 1443R on the bottom left