OPM is terrible. Even the academics realize it (I think). This paper evaluates the analysis. There's a caveat on pg. 24. GIGO. In my opinion, it's not just a caveat. It's a killer. I'm not sure what the overarching societal value to applying OPM to private, illiquid company valuations could be.

http://repository.upenn.edu/cgi/viewcontent.cgi?article=1035...