From what I can remember FCE outputs to Quicktime. If this is the case you should be able to use Apple DVD Studio Pro. This is much more professional with lots of options .. But it's rather expensive ..
X-rays, what is it that bothers you about iDVD? What version do you have? iDVD 08 is really fantastic I am blown away for the quality you get for the money.
You are aware that iDVD is only for developing the DVD content, menus and MPEG2 encoding and burning, right? You still render all your effects, transitions, etc in FCE. I only ask to clarify since you were calling it iMovie before.
As others have said, if you want complete control of your DVD with multiple alternate audio tracks, custom loops, jumps, etc , etc, you can buy DVD studio pro. Even the older versions will produce good DVD's, but it's a hell of alot of work.
Are you wanting to get into this semiprofessionally or is this a hobby, or what? Check out the demos of iDVD 08 if you don't own it, I think you will be impressed.