As I understood AMQP 0.9.1, the main benefit was that you could send and receive messages and configure your exchanges / bindings / queues in a broker-independent way, thus you were able to switch your broker implementation without too much headache.
Now, AMQP 1.0 only defines a wire-level protocol, so you actually have to know your broker specifics in order to implement most messaging patterns.
Then why would I favour a message broker that is AMQP compliant over one that is not?
If the broker implements AMQP 1.0, I'm still locked in with broker specific client code. With AMQP 0.9.1, I am theoretically broker independent but would most likely end up with RabbitMQ, since they seem to be the only ones to sincerely maintain the full support for AMQP 0.9.1.