A language with a type-system, a concise syntax and a well defined program and documentation structure ;-)

Seriously, I think Perl IDEs have a severe upper limit in functionality - syntax highlighting, capture stdout, debugger etc. The heavy-weight IDE features - refactoring, interactive documentation and debugging, UML modelling, project management, existing plugins - have a poor foundation to build from in Perl.

Most Perl IDEs I have checked out seem to reach this limit, then start adding bullshit features like Code Templates - Im happy sticking with a text editor. Contrast this with programming Java in Eclipse - woah!, vim/emacs and the cli look embarassingly quaint.

I tried EPIC about a year ago and it was pretty buggy, thanks for reminding me to drop by.