Last night I was charging a 2S A123 pack. Due to operator error (don't ask, I'm not interested in enduring an iquisition regarding my charging methods) I let the pack get to almost 12V at about 3-4A. The end of one cell blew out. The pack flew a couple of feet and landed on the floor. There was no smoke or fire just a bunch of black power and copper foil. Seems like a pretty safe cell to me - certainly no worse than NiCd or NiMH.

There will be attached photos if I can figure out how...