i'm having the same problem as mediumwell with redirect a non-member to registration page rather then showing a 404 page.
Here is how i got everything set up.
Create a Basic Free Level with access to all the pages except for Subcontractor Page
Create a Subcontractor Level with access to all the pages including the Subcontractor.
Set the Stranger Setting to Basic Free
Registration Page to none
Protected content page to Sign In (Which i created)
Override 404 with protected content - Yes
As a Basic Free (non-member) I get a Page not found when i try to access the Subcontractor Page. How do i redirect them to the sign in page?
Funny thing is if i Set the Stranger Setting to none, all the pages gets redirected to the sign in page.