>>Does everyone else really always hike alone?
For me, yes (at least most of the time).
My system is: poncho tarp (Golite or, Gatewood Cape), Vapr bivy, and Arc Ghost (colder conditions Arc Alpinist). Since my tarp is also my rain gear, I don't consider it to be extra weight. Most of the time rain gear is a must have in Oregon. The only extra weight is the bivy (7 oz). Very close to your 5.33 oz per person weight, Erin.
I have to agree with Doug, this is the most versitile system that I have ever used. No matter if it's hot, wet, dry, cold, or any were in between, this system just can't be beat. You can adjust on the fly: tarp only, bivy only, sleeping bag only, bivy and bag, tarp and bag, tarp and bivy, all three, or none at all. That's alot of options for very little weight.
>>Like James, I also have taken only the Vapr bivy. This is only when the chance of rain is miniscule. If conditions change, I know I can flip the bivy upside down or find some natural shelter.
Doug, great tip on turning the bivy upside down I never thought of that. Not to mention that your one brave man to go with only the Vapr bivy as your sole sleep protection from the elements.