Definitely adds to the bounce factor. Earlier this season I had some decently fat, bouncy dreads, and took many, many bounces off them. However, i actually ended up cutting them, mainly because of paintball. They drastically increased my profile, as they would not only hang/swing around, but expand the size of my mask too, especially with other headgear on. Also, they were waaaaay to hot, and just plain annoying when playing. Although they looked pretty badass
Now i realize the topic isn't about dreads specifically, but all the same things apply. Depends on your preference really, but IMO, not worth it for paintball alone.
<<<For example, check out my giant mug there, see what i mean? Just rock a couple headbands/wraps/beanie for bounce.