Leo, although your 100% right about the safety side of lipo's, i dont think the A123 or similar technology will be catching up any time soon.
The new range's of lipos that are beginning to hit the shelves now are getting seriously good. 40C continous and 65C burst ratings! in a 6000mA pack that featherweights can easily use would mean 240A continous, and 390A burst. In a 6s (equivilent to 24v) pack, you would be able to run a good amount of heavies with a battery pack that weighs about 800g, and fit in the smallest space . If your robot cant contain a fire from a lipo for 30-40 seconds, then it shouldnt pass a tech check with one in!