I'm defiantly a two spacer. Most of what I type is unformatted monospaced text (code and email) and when I do format things it is in some thing that doesn't care such as LaTeX. When I type things in I intend them to be interpreted as data (I don't use Word)
before they are displayed. The computer should do the work of figuring out how it should be set to look nice. Meanwhile while it is still monospaced code, it has nicely separated sentences.