I agree 10 mins is very short. how about 20 or 30 mins. How about forever?
I don't understand the vital information thing... The posts belong to the individual who write the posts.. we can't modify each others posts (as far as I know).
If the Poster can only modify his/she post, and forum's objective is to protect the Poster from "potentially destroying/making useless very valuable threads" that makes no sense to me.
I believe the poster should be able to Post, even create a personal Wiki of the topic as he/she wishes. And maintain control over that information.
The forum is a repository of ideas and comments and testimonials etc.
This approach would have the benefit of allowing consolidation of topic information and making it much more readable.
As an interested reader of, lets say, "exhaust mods" you could read in a single place what a contributor has to say about an exhaust mod.
You won't need to scan through pages of a thread written over months to compile the Poster's messages. He/she would have been able to modify the original post. It's not important to maintain the journally or the chronology of messages over their content.
The notion that we need to be protected from yourself; our typos, bad ideas we'd like to retract, updates we wish we could add to your original posts is unnecessary. This isn't Congressional testimony that needs to be protected.
That said, I realize we are all constrained by the functionality of the Forum Software. We can't make it do something it doesn't do. And I understand many forums work this way.
Thanks for your time and consideration.