Tents are great but its the pitching space, time, and weight and bulk for a tent you can sit up in.[i][/i]
For space (footprint) bivvies are best but as for time ,weight and bulk something like the Tarptent Moment is not all that different and does offer a lot more space inside as well as ventilation and views still out of bugs and rain.
Just over 2 lbs, 18"x4" packed, takes 2 minutes to set up (2 pegs only) or another minute to add another two pegs and the guylines in exposed areas.
(I am with Tarptent but have used the Moment a lot and it is what it was designed to be :quick and easy to set up)