The client handling it is ideal from a systems perspective, because the app won't forget to be fault tolerant on its connection to the server.

Its less ideal from a maintenance perspective, because there will need to be feature-rich clients in Java and C (with dynamic language bindings). Applications will be running many many versions of the clients. Also, for coordination, the clients will need to communicate, so there may be configuration and/or firewall issues for the app to resolve.

It will be interesting to see Amazon make this tradeoff for what I believe is the first time.