Hey Jacob - really great feedback. You hit all the points for me - every data point is different. For example, it seems that People Data Labs specializes in headcount data and has some interesting ways of getting that data beyond LinkedIn, or maybe more advanced based on a few reports I read over the weekend.
Revenue for private companies is indeed a tough one. Seems like most providers are inferring revenue based on head count so even more important that you get headcount right when revenue is downstream from it.