Docker is on my long term list (maybe) but the current system is fast, stable and requires little intervention so docker would have to offer a massive change not a step change to make it worth it.
I always default to things I know until the benefits are clear and it's worked out well so far.
Just to give more context, our use case is spawning Jupyter notebook in containers using JupyterHub and DockerSpawner so that each data scientist gets a personal ready-to-use environment to work with. With 4 data scientists we're beginning to reach the limits of the largest instance provided by our cloud provider and we're expecting to have more users soon. Actually our current cloud provider has just released a managed k8s service so that might be the way to go.
I highly recommend leveraging AWS, Google, Azure, etc services. Especially if you're a small business, spending a little for off the shelf tools that someone else operates and supports is going to help you big time.
Perhaps you'd be better served using more managed services, though?