So an update to my last blog post on the issue:
I have finally switched over to InteliJ IDEA and I'm really happy with it.
What finally made me switch was the fact that IDEA can easily work with Maven projects written for Actionscript while FlexBuilder can not. And the reason I needed to work with Maven projects, was because I needed to work with TeamCity for automated builds.
After being forced to switch, it turned out that the switch was very easy. I expected it to take me a week to get used to the new IDE, but in fact it only took me about 4 - 5 days. (I guess for some that is still considered a week, isn't it? )
I'm really happy with it. It's not the perfect IDE, it still has some issues of convenience. Like being very picky about properly defining the SDK being used for each module in a project. And while it works perfectly with maven, it doesn't yet work perfectly when you try to run Unit Tests through the IDE using the settings in Maven. But I am sure as the community usage of the IDE grows, these minor issues will be worked out. It certainly blows Flashbuilder out of the water though, in just about every way. This is especially true, since now Flash Builder doesn't even support design mode anymore. Oh Adobe, why have you forsaken us? And Greetings JetBrains, our new saviors!