I've recently figured out an all too obvious workaround for the vanishing spaces bug. Considering links, italics and bold basically cover 95% of all formatting needs I think some people may find use for it (it has cured my distaste for writing articles on LW).
1) Write a comment or PM in Markdown syntax. Post the thing.
2) Select the text and copy it straight into the WYSIWYG editor
3) Delete the original post or PM.
It is such an obvious solution, yet I didn't think of it for months.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.