<p>I don't see any problem with using the revision history in this way.  It seems fairly clever to me.  One thing you should be aware of is that if you have too many edits (10, I think) your answer will be converted to CW automatically.  However, you can flag your answer and the moderators can convert it back.  </p>

<p>I suspect the edit revisions are at least as stable as github.  Regarding the concern that old versions can be curated like comments, you should know that deleted comments still exist somewhere.  For example, moderators can see them, I believe.  (Users with >10k reputation can see deleted answers--and deleted questions, if you can find a link to them--but not comments.)  </p>
