Wow, a very quick and insightful post! Thanks!
I didn't think a filter would stop an impact, but had it mostly for reasons you stated, even outside of paintball. It sounds like if you plan on shooting photos you should be prepared in advance, and probably shouldn't just be like "Hey, I'm gonna bring my camera out into the middle of the next game." I think I'd be nervous about it no matter what I did, having never owned a DSLR and not wanting to wreck it :P
Another thought: telephoto lenses are probably the preference so you aren't "giving players away", right?