oh that suck for your brother! my family has been doing this for 3 years and really love it, we have stayed in some wonderful places locally and around the world. If I remember correctly homeexchange have some kind of insurance policy to cover damage? yeah I would freak out too if something like that was to happen to us, but so far we have had great luck (knock on wood).
OP, to answer your question, if you are considering joining homeexchange, a meetup is a great place to meet people and get some real feedback. I checked their main meetup site and found this one (
https://homeexchangeday.com/40e07192-cec6-4d21-b305-9c5e2ea12961) close to Silver Spring which is closer to me and I will try to attend that one (I love Locavino).