We use both and RabbitMQ is not a solution for this problem. Message handlers/listeners are equally susceptible to this problem on Heroku (or, generally, to being killed).

RabbitMQ can be configured to not ack messages where an exception was raised, so if you have a durable store and the code responding to messages is idempotent/retriable ,you are good to go. Such a system can be easily configured with resque jobs using resque-retry, so it's mostly down to how you design your jobs/listeners/message handlers and not the underlying tech