Welcome to the Q&A Forum

Hi Paulo, I can't think of any way to objectively measure whether it would make a difference or not, however, just putting my mind to work on it, there is a small possibility that it could be included in a trust algorithm; spammers are unlikely to be paying the extra to use them. Anycast DNS may also mean your site has a better uptime rate when parts of the Internet go down or be very slightly faster but I don't think it's worth doing just from a SEO perspective.

Paulo, you'll have to test the speed of your site yourself, but you can do so at a place like: http://www.uptrends.com/aspx/free-website-server-network-monitoring-tool.aspx It will display results from other countries and cities from around the world and help you decide whether or not you need a cdn.