I think that what you should use for scrim depends on where you live and what sort of terrain you train in. For the Wet Coast, where I live, most of us have cam screen, strips of old t-shirts and boxers (the old passion-killers, not poly-pro obviously), dark and black burlap, etc, with just a little light stuff to break it up. When I was in Edmonton, I saw a lot more light burlap and lighter scrim with a little dark stuff to break it up.
I always recommend to new guys to use what they were given on SQ/BIQ, and add what they feel is appropriate based on what they have (old shirts, cam screen), and what they see the Sr. guys in their Section/Platoon using for scrim. They might even have some extra scriml for them.