async producer and new ack levels

With 0.8, we now have ack levels when sending messages. I'm wondering how
this applies when sending messages in async mode. Are there any guarantees
at least that each async batch will wait for the requested ack level before
sending the next batch?

I assume there is still a disconnect between sending a message and really
knowing if it was delivered, in async mode. Is it necessary to create an
eventHandler to try to manage things in this case?

Perhaps, if acknowledgements are desired, with the efficiency of batch
sending, it would make more sense to use a synchronous producer, and use
the batch sending mode (e.g. send a list of messages).

Jason