I know you're swamped with other work. But wanted to make this suggestion before I forget it. And if it hasn't already been made...
I like the url modification feature.
I don't like what it does to the WordPress Lost password process.
I'm wondering if it would be possible to have a set of reserved keywords (question and answers) that would be disallowed and if those were included in the wp-login.php?url=query they would be processed by wordpress, or other plugins, as thought SLP plugin was not active.
That's my thought of the day.