1) Debugging becomes more difficult as line numbers aren't reperesnted correctly, nor the actual error. Often the error will be presented in the highest-up module used in your tree. I recommend having a script that will comment out the selfloader code while you are in development and put them back in when you are about to put things in production.

2) Many editors get confused by SelfLoader because your actual subroutines sit below the __DATA__ declaration. I don't know how to trick Emacs or VI into seeing these correctly, but JEdit maintains its highlighting correctly.

The speed gains in a non mod-perl environment are nice though.