We had considered enabling cache at some point in time as we build up our infrastructure. In particular our thoughts revolve around how to work in Redis as part of the stack and our business plan. Our desire would be to run Redis on a separate server with its own dedicated resources instead of adding it on to a droplet. The business plan is part of the issue here. In particular dedicating a server to Redis. We will be experimenting with some solutions such as running an Amazon AWS EC2 instance, or a Amazon AWS Elastic Search instance.
We have media and documents cached using Amazon's AWS CloudFront. This was simple to enable since our media and documents are stored on S3 (see Storage). Also the files are served from cache using the point of presence geographically closest to the website visitor.