I have used them in both the Holland, Resurgam and now the Dzik (U uPVC class) for about 3 years with good results.
No fires or explosions just one dead battery after only 3 charges (£25 down the spout.Boo Hoo!)
This may have been a faulty battery or the fact that I was not using a balancer charger then.
The Lipos I use are about 1800mAh capacity and give a "typical" duration of about 30 minutes which is fine for show or club use.
I now use a very simple Turnigy Compact Balance Charger C3 with good results.
I use a "home brewed" low voltage alarm which can be heard close too.
This could be improved but LED's need connecting up, waterproof connections etc. The commercial BEC's often seem to warn low voltage by cutting the throttle, which is not that noticeable in a sub.