perfSONAR as of October 2014 no longer supports PingER.

• perfSONAR is great if you have the resources to procure, install, configure and manage the performance measuring hosts. 
• PingER's network load is minimal, perfSONAR can make very heavy network demands.
• PingER makes measurements to hosts that respond to ubiquitous ping response request, i.e. no software has to be installed on monitored/remote hosts, perfSONAR only makes performance  measurements to other perfSONAR hosts.
• PingER has measurements going back 17 years, perfSONAR got started in the mid 2000's
• PingER has regular measurements to over 160 counties, perfSONAR has probably 20-30 countries.
• They are complimentary. perfSONAR is particularly good for measuring high performance links and on backbones, PingErR is good for end-to-end low performance links.