I can't offer any direct answers as I have never worked for any of these companies as an employee, I have only dealt with them from an external point. However, I think you might find the website Glass Door useful (glass door.com). This website gives you an inside glimpse of the company, which includes anonymous reviews by past and present employees, salary ranges for different positions in the company, etc. I hope that helps you in the meantime! :)
P.S. I see that you are in BK. I am thinking of making a move to NYC sometime in the near future. What is your take on the research institutions out there (as far as company culture, growth opportunity, salaries, etc.)?