Cloth is lighter. Both as a prefilter (small square of bandanna mateiral or similar) and as a coffee bag. To be honest, I don;t prefilter much, becuase the water I use (cascade mountains and foothills, eastern Oregon) doesn't need prefiltering.
I've used one cotton cloth bag for a coffee filter for a while now, and they work great. I bought a five pack for a few bucks at the local overpriced groovster grocery boutique, and gave one to my mom. One used one lives in my pack and three others are in teh kitchen box in our store room.
After making coffee, I dump it, scatter the grounds, and attach it to my pack to dry out during the day. Works great.