I know there have been questions like What is your favorite editor/IDE?, but none of them have answered this question: Why spend the money on IntelliJ when Eclipse is free?

I'm personally a big IntelliJ fan, but I haven't really tried Eclipse. I've used IntelliJ for projects that were Java, JSP, HTML/CSS, Javascript, PHP, and Actionscript, and the latest version, 9, has been excellent for all of them.

Many coworkers in the past have told me that they believe Eclipse to be "pretty much the same" as IntelliJ, but, to counter that point, I've occasionally sat behind a developer using Eclipse who's seemed comparably inefficient (to accomplish roughly the same task), and I haven't experienced this with IntelliJ. They may be on par feature-by-feature but features can be ruined by a poor user experience, and I wonder if it's possible that IntelliJ is easier to pick up and discover time-saving features.

For users who are already familiar with Eclipse, on top of the real cost of IntelliJ, there is also the cost of time spent learning the new app. Eclipse gets a lot of users who simply don't want to spend $250 on an IDE.

If IntelliJ really could help my team be more productive, how could I sell it to them? For those users who've tried both, I'd be very interested in specific pros or cons either way.