Some time I use the "raw" html editor to write special post that need code inside it. As known, the rich editor is not always compatible with such code. So, when reopening a post (and forgetting that it has inside spacil code) one can destroy the original content.
If possible, store the "last" editor used for the post and open the post with such an editor.
Or give the possibility to have a real pure html post, marked with a flag, that bypass the texturize filter and other embedded post typographic transformation filters.