Well, we have different workflows. I pre-render the sequences since I often need to do it anyway when using plug-ins like Magic Bullet. Given that I have to render the effects, I select the codec in the sequence, usually AIC, let it go, when I'm done I use "Current settings" to export the whole footage in a couple of minutes. Then I drop the resulting QuickTime file into compressor and do the final transcoding.

I tried MB once and couldn't see any reason to wait for rendering just to get a "look." The audience will never know I chose not to spend time getting look "A" if they see look "B." So, if B is RT -- why not?

In short, if it's not RT -- forget it. :)

Oh Brother Where Art Thou used special coloring techniques that took weeks to do. They did a test render on certain frames from scenes and then decided on a final look, and did it.

Maybe you could do something similar...certainly MB doesn't take weeks to render...

Of course this is now entering the field of image grading/color correction, aestethic choices etc. etc. What I like about the digital grading techniques like Magic Bullet is the the ability to shift the gamma settings further and more finely of what you can do in camera. It's the digital world equivalent of, partially, what is done in the film lab. There is a free plugin for FCP, http://www.pureandapplied.com.au/ , that has a "film gamma" effect that can be used to esperiment with the idea. MB gives you more control but the concept is similar. The way that you can shift the gamma and then tweak it until it gets right is a way of improving the look of you footage that I appreciate a lot. One of the great luxuries of shooting in digital. Another feature that I like is to bet able to finely control the look. Color shift (warm/cool), diffusion and many other factors. It's just a matter of getting the image where I want and one of the ideas behind TrueColor: get the most neutral look in camera in order to keep all the bits intact and ready for digital grading.