I know I dont post often but I much prefer the RFL and Robowars forums editing features. If you post a link that doesnt work, it could take a couple of days for someone to notice. I think its much better to change the original post than to keep posting until you get one that works.
Like Daniel said, its nice having a forum post that everyone knows always contains the latest info because it keeps getting edited. Provided everyone is aware of the system it can work very well.

10 minutes is much too short for me.

If someone deleted their own post, would a record be kept of it anywhere? (i.e. would a mod be able to prove they posted something defamatory or whatever?)

I just thought, this sounds a bit like the gun laws arguements. Is it the posting tools that annoy people or the posters? I think the people that would abuse the tools are the ones that are annoying anyway. They need to be controlled, not everyone else.