Sounds great! I like every point but one. I'm not enthused about general users being able to see my post edits; I edit for the purpose of (1) fixing typos (sometimes no amount of re-reading seems to catch them before I hit Submit), (2) making factual corrections, or (3) phrasing things more diplomatically. I don't feel like getting pounced on over something I already fixed, when I'm having an intense debate with someone who decides to click through my post's change history looking for any vulnerability they can find.
More importantly, new users have a tendency to give too many personal details, not realizing that even the Private forum can be trawled by believing JWs who have registered for the purpose of getting people they know in trouble. Also, sometimes users have also posted anonymized text such as emails and failed to totally scrub a name or address from the text. Making the old text versions viewable for everyone will therefore make it even harder to fix leaks of personal information, as opposed to the current system where they at least have half an hour to completely remove that information from the sight of inquisitive users and Google. Half an hour is usually not enough time, however, to warn a user of such a problem and for them to see that warning and take corrective measures; but it's better than nothing.