A serious fire could happen with any recorder with built in Li-ion/Li-poly batteries and especially with an external battery pack. I'm switching to newer LiFePO4 batteries which are much safer. They have less energy density, though more than NiMH, but it's worth it.
The fires produce a lot of noxious smoke and it would be a disruption to the show at a minimum! Property damage is highly likely and injury is possible. If a tapers rig burns up you can bet that the venue will be very wary of allowing tapers to come back.
