A couple thoughts on the filters...
Red is normally used to protect night-vision and it does it pretty well; one thing it doesn't do well is show blood. When I worked patrol, I kept a red filter on the light for building searches. Something about the beam from a 6p catching a floor to ceiling mirror
Friends in the medical world use the blue filters because it helps the night vision and allows them to find the blood, which may or may not be an issue.
IMHO, the 6P or 6Z are the way to go, however I have never used either of the 9's.