Hey sure, I should have been more specific. The enhanced networking in AWS requires ixgbevf at least version 2.14.2. In addition we had random hardlocks with ext4 under the centos7 kernel. Also we had a lot of difficulties running docker on EBS disks with the device manager driver - hard lock ups randomly. That's all I recall off the top of my head. All these issues disappeared upon moving to Ubuntu 16.04 on a later kernel. Centos7 was great for us otherwise, it just didn't seem to work out so well with Docker + AWS.
Disclaimer, I happily work for RH and today's blog has me ear-to-ear grinning.