lol. I can absolutely confirm that a52decX is capable of splitting 5.1 AC3 into six AIFF files, because I have used it to do exactly that several times. This functionality is what enabled me to make my 70mm mix for Star Wars, since editing the LFE from the special edition and adding it to the original version of the movie was one of the key concepts behind the entire thing.

There is an option in the window to select output: by default it will downmix to plain stereo, but you can also select 'Dolby' which is presumably a matrixed Prologic version, and most importantly the individual output, which gives each channel its own AIFF file. The channels are clearly named so you know exactly which one is which. I agree that it would have been very helpful if the program description clearly spelled out this capability; Mac3dec never worked for me, so I had to look long and hard before I found how to do it this way. But I promise you, it does work--it's like a hidden Mac audio gem that nobody seems to know about.

Have you ever used Avidemux? Right now I'm looking into editing options and this one seems to have a lot of the things I'll need, particularly the ability to edit mpeg2 files without re-encoding. Mpeg Streamclip can also do this but it lacks Avidemux's ability to precisely select individual frames. Current version only works in Snow Leopard, which initially caused me to pass over it until I realised that my external drive has my dad's 10.6 install on it. ;)