I've got a return of around 9% these days. I've been investing in Lending Club for 4 years or so.
This year the value hasn't been in the return itself (I'm slightly below previous years), but its been in the return relative to the rest of the market. In years where the stock market has been really strong, LC has underperformed for me.
That said, I feel like the really good opportunities in Lending Club have dried up. They've standardized their process and put up really strict loan requirements, so everyone who gets a loan is somewhat credit worthy. I actually like the F and G notes, but there aren't very many.
You can sell/buy notes on the secondary market (folio), but I have found you have to sacrifice value in order to unload your notes, so it almost always makes sense to keep them (unless your willing to give 5% of the value in order to get the cash). There are some buying opportunities there, but selling is tougher.
PS also beware that Lending Club does lots of business with institutional inverstors. They have people working on this full time with much better analysis than you or I can do. I feel like competing with other investors at Lending Club is a lost cause, but using Lending Club against other investment types could be good.