[meta] Comments limit too short

I've noticed that the current limit for comments is 300 characters. It seems a lot but is not. Almost always I'm finding myself struggling to keep my comment `understable` for the OP and at the same time keeping it under the 300 char limit. And if I want to add an url, then I'm doomed. Also seems that the `convert to comment` feature [also fails](http://help.openerp.com/question/2039/meta-convert-to-comment-feature-gives-a-502-error/) on the cases where the answer has more than 300 chars. So, is there a quick way to configure this and allow at least 500 characters. Once again, on most SE sites, is limited to 600 characters.