Once you turn it back to into 1080P you will have a lot more scope for creative work if your final output is going to be 16x9 at 720x480
For example if your starting images are HD then you can zoom in on a characters face by a factor of at least two and still not get noticable pixelation at SD res, it will allow you to crop shots etc. without degradation in your final piece.
I'd go Sin City on it and go mostly B&W with some colour or tints for particular scenes, a bit of red never hurts when travelling down the dark side.