"The E blankets rip like a man who'd had too many beans."

That's exactly what happened last year to one of our rescuers on a rescue during a blizzard. 
He pulled out his "emergency" bivy, the wind shredded it, and left him with a small piece of mylar in his hand. 
If it's really for an emergency, it needs to be strong enough to trust.

I make a waterproof/breathable bivy with no frills that weighs under 11 oz.  I just used it last weekend on a trip on the Mt. Whitney trail.  I used it inside a tent just to protect my bag from spills while eating.  No condensation.  If it rains, water resistant won't cut it.  If it doesn't rain, then a non-breathable bivy just gets you wet from the inside.  The non-breathable bivy will let you survive the night, but it's far from comfort.  The Mylar type are good for maybe 1 night.

I'm 6'2" and almost every lightweight tent is too short.
I really like the REI Half Dome 2 Plus at $199
http://www.rei.com/product/794296/rei-half-dome-2-plus-tent
I know it not real light, but it's got room and won't bust the bank.

Dave

I laugh every time I watch that video.

Mike, I was really set on making a Uber Bivy during summer 2010.  However, for a couple, I prefer a tent.

For my rescues I built the Double Trouble.  With a person on each side they function as the pole to keep an open volume between them.

http://www.milesgear.com/DoubleTrouble.html

Dave

I thought some of you might enjoy a video of a bivy test.

Testing the Uber Bivy

Most bivy sacks are just too small.  Mine is 8 ft long, 36" wide at head and 26" wide at foot, and 24" high.
It will fit 25" wide pads and lets me sleep on my side and roll over easily.  Fully waterproof and very breathable.

Dave

As a mountaineer and search and rescue I use a bivy a lot.  I'm usually about treeline and like not having to rig a tarp.  Just throw down the bivy and get inside.  After several bivy sacks I decided to make one that was big enough for gear and to get dressed inside.  After people saw me testing prototypes it turned into a cottage industry.  This is waterproof / breathable and no condensation.

MilesGear Uber Bivy
http://www.milesgear.com/UberBivy.html 

Dave