Redis vs Service Bus for pub/sub scenario
Don't use Redis for this. Redis PubSub isn't reliable (it's fire-and-forget). What would happen if no one is listening when Redis publishes a message? It's lost forever, and this means that your services won't be synchronized...
Maybe you didn't hear about Azure Pack. It's not a full Azure on-premises, but it includes Service Bus. It should be no issue if you use it from the public or private cloud.
Note that you might be able to implement reliable messaging using Redis, but not on top of default pubsub.
A possible alternative to both Redis and Service Bus should be RabbitMQ.