Thanks for all of the feedback.
It sounds like Falcon5000 has tried what looks like the Extreme Pro-Tech Bag. His new
thread shows some screen shots of an identical looking product. Guess that one is out.
I guess I'm leaning towards the AMK Heatsheet bivvy or the Tacoma Mountain Rescue Storm Shelter. They seem fairly similar but I may have to do some additional homework.
For summits and backpacking, the Thermo-Lite bivvy will always be with me. I really trust it. I like the adjustable opening which keeps you from sweating.
I may also invest into a vinyl military poncho that snaps on the edges and is so versatile. Use it when wanting a light load in combination with the AMK Heatsheet bivvy or the Tacoma Mountain Rescue Storm Shelter.
Keep the feedback coming. I appreciate the input.