Just wanted to let you know that DAP now works with 2Checkout.com.
The new file is dap-2co.php and it has been rolled into the existing dap_v4.2.1.zip file, and is available for download in the member's area (if you already are on 4.2.1, you will have to download the zip file again, sorry!
– Veena & Ravi
P.S: By the way, we've actually completed integration with WP eStore too!
The code and documentation for that will be available shortly.