Well, reglevel has been awesome in terms of sorting new registrations into appropriate user roles. One little loophole though: on the login and forgetpassword pages, there is a link to Register that brings the user to the default register page. Thus if a potential new user ends up on the login page (not uncommon) they will find a link to the register page. When they click to register, they will not have been sorted by the user roles set up with reglevel because they won't have gone through the reglevel url for that role. Instead, they will be registered with the default role assigned by WP. As similar situation exists with the forgetpassword page.
The quick fix to this seems simply to be to remove the "registration" link in both the log in and forgetpassword pages.
But I am a coding illiterate so all I can do is post here, hat-in-hand, and ask for help :) Thanks for reading.