I have lent some money using prosper, and I am about to try out lending club in the next couple of days, as soon as my money goes through.
To me the stats are irrelevant. I don't think people are less likely to default because it is one site rather than another, in the end the default rate are going to depend more on credit and economy than anything else. IMHO.
You can see how lending club goes on my blog in a couple of weeks. If you are interested, they are offering a referral deal like prosper's $25 after you fund your first loan.
I think the best solution is to make the web a lot less anonymous. Their needs to be a clear way to identify who is doing what. I know I know about privacy and all those concerns. If the internet was the real world, then spammers would be like people putting up thousands of signs in Wall mart every day telling people to buy things in a back ally somewhere. Wall mart simply would have the people thrown out or arrested, but becuase we can't track these people down effectively we have NO recourse.