We have also created a report that summarizes and aggregates manged DNS performance and availability globally and regionally, features and pricing. It is still under development, and we intend to sell it in the future, but I'm happy to share it, and would appreciate feedback (caution it is a 10mb file): http://dl.dropbox.com/u/20765204/CH-DNS_Report-12_2011.pdf - it is a good resource if you are evaluating different providers.