[Patrick]

I always charge mine in a lipo sack, and at home I also put the lipo sack in a metal toolbox. I haven't had anything go wrong charging a lipo, but I'm not going to stand in the garage for an hour + watching a battery charge. And at racing you can't watch it all the time, because of marshaling and things like that. So I feel a bit better having it in the lipo sack.
The only lipo charging accident I have seen was when another racer was using the same charger for the lipo's in his G2R and the nimh's in his 1/10th buggy. He forgot to take the charger off nimh settings and plugged in his 2s 4800mah orion pack. Luckily he saw the lipo swell up and unplugged it before we got to see fireworks.
Lipo sacks or other protection is good, but prevention is more important. The biggest thing for safety I think is to always use a charge through balancer, and always double check your charger setting before you hit the start button.