Tyvek is AWESOME for condensation prevention. Be aware that there are many weights and kinds of it, tho.
I picked up the tyvek version of the Sublite tarptent for a specific reason - Tyvek reflects sun rather than sucking up the warmth, and if you're gonna be sleeping during the day and want a bugproof tent, there you go. Even under an open nylon tarp at reasonable (70-80F) temps, I've found that I heat up a lot. Not so with Tyvek.
It proved to be absolutely lousy for ongoing heavy rain, tho. Soaked up the water and weighed a ton. Left gallons of water in the bathtub floor. (I was a meanie and left it til morning after I bailed off to the car to keep my quilt dry. Drips were coming in through the apex of the tent, and the fabric was so heavy it sagged into the bugnet, resulting in dribbles on my quilt.) I expect that it would keep 2-3 hours of moderate showers at bay. That's all I want it for, when I'm on a search and rescue, and we catch that midday nap before we head back into the field. It's a summer tent. It's been great on some of the humid coastal campouts, only tent in the group that does not drip condensation by morning and require a lot of time in the sun to dry.
The tyvek sublite would go on any desert hikes, where I'd want to sleep in the hot afternoon and keep out scorpions.
The hydrostatic head of tyvek is pretty poor.