Along similiar lines, my company is running an ongoing series of teardowns that pick out user experience obstacles on well known websites. We do a pretty rigorous analysis, both for onboarding and everything else.

So far we've done a saas product (http://www.smoothconversion.com/blog/mouseflow-web-funnel-te...) and a big media site (http://www.smoothconversion.com/blog/everyday-health-web-fun...). More are in the pipeline.