As the author of one of the two systems I don't feel super well at comparing Disque and Benstalkd, but I guess, as Disque matures, people informed about both systems will compare them. However an obvious difference is that Disque is "internally" distributed and federated, while Benstalkd requires the client to take care of managing multiple nodes.
One guy that I think is often overlooked is beanstalkd (https://github.com/kr/beanstalkd), especially with regards to 2). Have you ever taken a look at the project and if so, how do you think it compares to your vision for Disque?