Green screen Vs. Blue screen

DV handles colour sampling of green better than blue due to how the codec operates. So there is slightly more information in the green channel as opposed to the blue. I have however seen people get good keys out of blue...well, as good as you can get from DV.

In general it just seems green is more workable when it comes to a lot of "human" talent as green is usually absent. Blue is a little more common in clothing (try keying jeans with bad lighting). Keeping this in mind you can of course still make use of the blue space.

Best thing I suggest is to do a test key on both with the camera and see. What may take you a couple of hours may save you days in the end. It may even reveal some lighting problems you would later encounter etc.