Sorry for posting on something so old, but I figured I should stop lurking!
I've been using Lending Club for about a year now. I think it's a pretty good investment source, but I've only put 1k into it as a test. After a year, I have a calculated NAR of 7.52% which isn't too bad, but is a lot less than it seems you could previously get through the service. I'm waiting to see at tax time how difficult things are (only have a taxable account with them) and use that to measure if I want to continue using the service.