We recently migrated our clusters from EC2 to Appnexus are and are very pleased with the results.
The bonuses we saw were: -- There servers are faster, especially disks -- The cluster performance does not seem to change peak/off-peak (it did very noticeably on Ec2) -- Appnexus gives you a VLAN, which is basically a firewall ring-fenced network which makes it very easy to setup cluster and servers that use it in a reasonably secure way. Feel free to contact me off the list if you need more details. Regards Boris
