Holy crap, film! Try this:

Download Marcie.
Import her into a new After Effects 7.0 project.
Set the project to 32 bits per channel (float)
Set your Project Working Space to Linear Adobe RGB
Select Marcie and File > Interpret Footage > Main
Click on More Options
Under Conversion Method, select Kodak 5218 ICC Profile
Hit OK
Hit OK
Drag Marcie to the Create Comp button
With the new comp's View active, View > Proof Setup > Kodak 2383 Theater
Select View > Proof Colors (switch it from unchecked to checked)

You're now working with a Cineon file in linear, scene-referred float, and accurately previewing how your work will looked filmed out on Kodak Vision film stock.

When you want to output back to log:

Create an output comp that contains your linear Marcie comp
Set Proof Colors to Unmanaged for this comp's view (Proof Colors should be checked)
Apply the Color Profile Converter effect to the layer
Leave Input Profile set to Project Working Space
Set Output Profile to DPX Scene - Standard Camera Film
Very important: Set Intent to Absolute Colorimetric

Output this comp to a Cineon sequence and it should match the original Marcie source.

You've now fully round-tripped a color managed, linear floating point film compositing pipeline. I don't know of any other compositing application that ships with this capability, "high end" or not!

But wait, there's more! Want to bake this film-look LUT into some NTSC video dailies?