I think if you are using 2ch then always run POLY for simplicity, but if you are running 4ch or more then your best option is MONO. I haven't found any software that I am comfortable with to use POLY for a 4ch file. I would love to use POLY for my 744 files, but I also despise learning an entirely new workflow at this point. I tried my damnedest to make the switch to Audition CS6, but the workflow just doesn't seem as intuitive to me as Wavelab 6. I wish I could sit a day with an Audition expert and have them try to convince me otherwise.