These pics took about 5-10 hours. It depends when you think the image is done, the longer it renders, the less noisy image. But yeah around 10-20 hours are normal. But then again, if you render with MR and want the same quality you can't expect to render in 1 hour either. Pros: Don't have try tons of settings to get a nice render. Almost "press render and wait". You can spend the time tweaking the materials instead. Cons: It takes time. You can't optimze the renders that much.