I'm in the process of choosing technologies to build the level editor of a Flash RPG game.

On one side I can use AIR and build a ingame level editor that's probably going to give the best result. The problem is, I think it will be very hard, I don't have good memories using the UI libraries of AS3. I think that would take at least 3 more times (to build the editor) than the other approach.

Or I can use some mature set of tools to build the editor, like the ones commonly used with C# or Java.

The question is: Is it worth the trouble to build the editor in AIR? Or using a stand alone editor is just fine?

EDIT: Me and my team are the only people using this editor.