I should know the answer to this question but I'm not as sure as I would like to be.

First, the situation is this: I have hours of Red R3d files (4096 x 2304) and Panasonic P2 MXF footage (1920X1080) to edit together for a one hour program.

I can work with both natively on the CS4 timeline. With that being the case, what would be the benefit, if any, of encoding them all to cineform?

I'm sure there's a good reason...I just can't find it.