I have my own custom CMS that I'm currently using to manage one of my larger sites. I'm currently in the midst of adding new functionality that will allow users to comment on reviews, news, articles & tips throughout my site.

The site currently supports user accounts and I'm trying to figure out whether I should restrict commenting on the site to either registered users or whether I should open it up to submissions from all users even those without accounts.

The way I see it is that it's probably better to restrict commenting on content throughout the site to registered users to reduce the amount of comment spam. That in conjunction with a CAPTCHA should do the trick...

Let me know what you think and advice would be greatly appreciated.

Thanks