I have an IPN script for PayPal, and as I can only rely on a log file to debug it and it's hard to maintain a testing server (and to test even for I am a one-man team), I am considering using cURL to run other scripts which would handle sending of emails, logging into database and updating of logs.
This way, if I have to send a new email (for some reason, clients never made up their mind), I don't have to tangle with the IPN script. Not just that, if for some reasons those new additions cause a FATAL error, the original IPN still runs. Is this a good idea?