Comments by unregistered users

you answered your own question.

Its controlled inside wp-comments.php @ line 35:

if ( get_option('comment_registration') )
die( __('Sorry, you must be logged in to post a comment.') );

and so you understand what you are trying to do, youre going to make it VERY hard for ppl to comment, since IF you redirect them to the registration page, they MIGHT register, but having done so, then they will need to come back after getting an email, and guess what.. by that time, they have forgotten what it was they actually wanted to say in the comment.

In other words, its a pita for them. If it were me (and I mean no disrespect when I say this).. your site would go in my shitcan.

The average surfer isnt going to jump through countless hoops to leave a simple comment.

fair point, how do I ensure that I know who is commenting, and ensure I get some valid information about them on the comment form?

require that they register to comment .. just dont redirect them?

Take a look at the Options:Discussion page…