I don't really have a "chief" thread to link to - perhaps
this one would do - but there have been several discussions about the inherent challenges of loaning Bitcoins, most of which boil down to "how can you have a system of trust when transactions are anonymous?" Have you chosen a strategy to deal with this? Or would it be less of an issue with credit unions for some reason? (To be honest, my understanding of CUs vs. banks is a rusty.)