Docker container to host reference application and library?

Recently I am considering to migrate from AMI to Docker Image
for the reference repository. Thinking about launching 20 or more on-demand AWS EC2 c3.4xlarge instances for WGS data analysis.

===AMI===

Pros:
    Fast to start
    No installation required
    No configuration required
    Secure

Cons:
    AWS only
    Building AMI is a little time-consuming
    Version control is tricky
    Volume size will increase gradually


===Docker image===

Pros:
    Easy to build
    Deploy on any cloud or local platforms
    Easy to tag or version control
    Seems more popular and cooler

Cons:
    Where to host repository?  The Hub or S3? Many considerations
    Pulling images from one repository on lots of worker nodes at the same time is not applicable. Networking would be challenging.



Definitely need more time to do lots of tests. Work in progress...