I believe in riding as fast as you feel safe. After all, no one knows when a tube will pop on the way down. Live to ride another day is very important.
At the same time, my max downhill road speed used to be 25mph. Now it's 40mph (assuming wide smooth roads and no curves in the road).
2014 Liv Lust
2013 Specialized Fate Expert with carbon wheelset (sold)
2012 Specialized Amira Elite
2010 Santa Cruz Juliana with R kit and Crampon pedals (sold)
2011 Specialized Ariel Sport,suspension post,Serfas Rx Women's Microfiber saddle (sold)