I just finished sewing a Bug Bivy that is a blend of several styles.
1.9 oz silnylon floor, noseeum netting, and a #3 zipper in the ridgeline. It weighs 10oz which is fine for me due to the added durability. Most of my trips are well into Canada and durability is an important factor.
For most of the year bugs are an issue for me and I'd prefer to avoid the possibility of Lymes.