Hi Jono,
I've never been able to find a way to do what you're looking for, and it's something that I would really LOVE to see.
Just an explanation for those who were wondering about a use case on this, I most frequently need this when doing film stuff. Here's an example from a fairly simple project I did recently.
Production audio (dialog 'n such) -> ProdAud bus -> Master
Cello 1 -> Cello bus (automation and stuff) -> score bus -> Master
Cello 2 -> Cello bus (automation and stuff) -> score bus -> Master
Piano -> Piano bus (automation) -> score bus -> Master
Bowed metal -> perc bus (automation) -> score bus -> Master
Misc perc -> perc bus (automation) -> score bus -> Master
In this case each bus represents an instrument group and a stem. The score bus has automation for the entire score. Since many of the editors I work with like to have stems, it would be REALLY REALLY handy to be able to bounce each bus (or track) to a separate file while still honoring the bus fx and automation. If we had that I could export each stem in one pass, zip them up and send them off instead of doing one pass for each bus to keep my automation intact.
I've given some thought to using aux tracks and then selecting them for my bounce source, but the problem is the (absolutely required) "score" bus. Since it represents automation for the entire score and has multiple "stems" feeding it I think I'm going to run into the same problem.
Dean