Just saw a report from the U.S. Government Accountability Office (GAO) comparing pre and post privatization (or semiprivatization in the casse of the UK and FRG) of air traffic service provideers. It is a 50,000 foot view but provides some box scores (or league tables) for comparison and draws some general conclusions but no recommendations or determination of good or bad.
URL is
http://www.gao.gov/cgi-bin/getrpt?GAO-05-769.