I do and it's great. It doesn't have some MQTT features sush as persisted messages or QOS 2 but if you don't need that, it's a fine MQTT broker.
Wait, what are you talking about? RabbitMQ does have persistent messages, you just need to set the queue as "durable", and the messages persist even during failures.
Indeed I'm a bit confused. I remembered about having to find a workaround because I couldn't use retained messages. It's actually not working only for subscribers with wildcards : https://github.com/rabbitmq/rabbitmq-mqtt/issues/154