There are two versions of RazorNav. RazorNav Lite is a simple forward and backwards PHP script – it appears to be lacking a dropdown menu and a full archive calendar page like the ATP script. RazorNav Pro has not yet been released but will apparently be sold on the website soon (no pricing available yet). While there really aren’t any solid details about the capabilities of RazorNav Pro, it doesn’t look like it will do anything more than ATP, which is available for free.
Now if someone would take the extra step of creating an ATP-like script that automated the management of multiple comics on one site and allowed for the option of creating a unique home page that could show some or all of the various comics (for example, the most recent comic of any of the independently archived multiple comics on the site), that might be worth something extra.