GR8ADV
Explorer
I would not recommend a bivy. I use them for extreme winter conditions when a tent is not feasible (Alpine climbing), or as a backup shelter in the summer if I need to be fast and light and only require a shelter if the weather turns. If I KNOW ahead of time the weather will be bad, the last thing I want is a bivy. You can retreat to a tent to wait out bad weather. Doing it in a bivy...sucks.
I think you could be well served with a Terra Nova Laser Comp 1. http://expeditionportal.com/field-tested-terra-nova-laser-competition-1/
It has elements of tarp living if you just use the shell and not the inner tent body. Like a pyramid, the hoop architecture is incredibly strong and holds up very well in high wind and with snow loaded. It has far better livable space. Pyramids stink for livable space with highly sloped walls and that center pole is a pain.
Another great option is the Hilleberg Enan: http://us.hilleberg.com/EN/products/yellow-label/enan/enan.php
I fully disagree that just going to a 2-person tent makes for the better 1-person experience. That's categorically incorrect. This is about feature and square footage. Some 1-person tents rival the space of some small 2-person tents. You have to assess livability on a tent by tent basis.
You might hold out a bit and wait for Nemo Equipment's new system they designed ideally with bikepacking (mountain bike travel) in mind. It is a comprehensive tarp, bag and bug bivy system that is really slick, very storm worthy, and exceptionally light. But, it works best as a whole system.
+1 on the Hillebergs. I have two of them. I have yet to find a better made tent. If you want quality that will likely outlast your travels, they make the quality you need.